Commit Graph

4019 Commits

Author SHA1 Message Date
George Amanakis 34ce4c42ff
Fix a race condition in dsl_dataset_sync() when activating features
The zio returned from arc_write() in dmu_objset_sync() uses
zio_nowait(). However we may reach the end of dsl_dataset_sync()
which checks if we need to activate features in the filesystem
without knowing if that zio has even run through the ZIO pipeline yet.
In that case we will flag features to be activated in
dsl_dataset_block_born() but dsl_dataset_sync() has already
completed its run and those features will not actually be activated.
Mitigate this by moving the feature activation code in
dsl_dataset_sync_done(). Also add new ASSERTs in
dsl_scan_visitbp() checking if a block contradicts any filesystem
flags.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #13816
2023-02-13 16:37:46 -08:00
Prakash Surya 13312e2fa1
Reduce need for contiguous memory for ioctls
We've had cases where we trigger an OOM despite having memory freely
available on the system. For example, here, we had about 21GB free:

    kernel: Node 0 Normal: 2418758*4kB (UME) 1549533*8kB (UE) 0*16kB
    0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB =
    22071296kB

The problem being, all the memory is in 4K and 8K contiguous regions,
but the allocation request was for a 16K contiguous region:

    kernel: SafeExecutors-4 invoked oom-killer:
    gfp_mask=0x42dc0(GFP_KERNEL|__GFP_NOWARN|__GFP_COMP|__GFP_ZERO),
    order=2, oom_score_adj=0

The offending allocation came from this call trace:

    kernel: Call Trace:
    kernel:  dump_stack+0x57/0x7a
    kernel:  dump_header+0x4f/0x1e1
    kernel:  oom_kill_process.cold.33+0xb/0x10
    kernel:  out_of_memory+0x1ad/0x490
    kernel:  __alloc_pages_slowpath+0xd55/0xe40
    kernel:  __alloc_pages_nodemask+0x2df/0x330
    kernel:  kmalloc_large_node+0x42/0x90
    kernel:  __kmalloc_node+0x25a/0x320
    kernel:  ? spl_kmem_free_impl+0x21/0x30 [spl]
    kernel:  spl_kmem_alloc_impl+0xa5/0x100 [spl]
    kernel:  spl_kmem_zalloc+0x19/0x20 [spl]
    kernel:  zfsdev_ioctl+0x2b/0xe0 [zfs]
    kernel:  do_vfs_ioctl+0xa9/0x640
    kernel:  ? __audit_syscall_entry+0xdd/0x130
    kernel:  ksys_ioctl+0x67/0x90
    kernel:  __x64_sys_ioctl+0x1a/0x20
    kernel:  do_syscall_64+0x5e/0x200
    kernel:  entry_SYSCALL_64_after_hwframe+0x44/0xa9
    kernel: RIP: 0033:0x7fdca3674317

The problem is, for each ioctl that ZFS makes, it has to allocate a
zfs_cmd_t structure, which is 13744 bytes in size (on my system):

    sdb> sizeof zfs_cmd
    (size_t)13744

This size, coupled with the fact that we currently allocate it with
kmem_zalloc, means we need a 16K contiguous region of memory to satisfy
the request.

The solution taken by this change, is to use "vmem" instead of "kmem" to
do the allocation, such that we don't necessarily need a contiguous 16K
memory region to satisfy the allocation.

Arguably, a better solution would be not to require such a large
allocation to begin with (e.g. reduce the size of the zfs_cmd_t
structure), but that'd be a much larger change than this "one liner".
Thus, I've opted for this approach for now; we can always circle back
and attempt to reduce the size of the structure in the future.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Prakash Surya <prakash.surya@delphix.com>
Closes #14474
2023-02-13 16:35:59 -08:00
Alexander Motin 87a4dfa561
Improve arc_read() error reporting
Debugging reported NULL de-reference panic in dnode_hold_impl() I found
that for certain types of errors arc_read() may only return error code,
but not properly report it via done and pio arguments.  Lack of done
calls may result in reference and/or memory leaks in higher level code.
Lack of error reporting via pio may result in unnoticed errors there.
For example, dbuf_read(), where dbuf_read_impl() ignores arc_read()
return, relies completely on the pio mechanism and missed the errors.

This patch makes arc_read() to always call done callback and always
propagate errors to parent zio, if either is provided.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #14454
2023-02-13 13:21:53 -08:00
Richard Yao 66953686c0 Add assertion and make variables unsigned in abd_alloc_chunks()
Clang's static analyzer pointed out that if alloc_pages >= nr_pages
before the loop, the value of page will be undefined and will be used
anyway. This should not be possible, but as cleanup, we add an
assertion. We also recognize that the local variables should be unsigned
in the first place, so we make them unsigned. This is not enough to
avoid the need for the assertion, since there is still the case that
alloc_pages == nr_pages and nr_pages == 0, which the assertion
implicitly checks.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14456
2023-02-06 11:10:50 -08:00
Richard Yao cfb49616cd Cleanup: spa vdev processing should check NULL pointers
The PVS Studio 2016 FreeBSD kernel report stated:

\contrib\opensolaris\uts\common\fs\zfs\spa.c (1341): error V595: The 'spa->spa_spares.sav_vdevs' pointer was utilized before it was verified against nullptr. Check lines: 1341, 1342.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\spa.c (1355): error V595: The 'spa->spa_l2cache.sav_vdevs' pointer was utilized before it was verified against nullptr. Check lines: 1355, 1357.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\spa.c (1398): error V595: The 'spa->spa_spares.sav_vdevs' pointer was utilized before it was verified against nullptr. Check lines: 1398, 1408.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\spa.c (1583): error V595: The 'oldvdevs' pointer was utilized before it was verified against nullptr. Check lines: 1583, 1595.

In practice, all of these uses were safe because a NULL pointer
implied a 0 vdev count, which kept us from iterating over vdevs.
However, rearranging the code to check the pointer first is not a
terrible micro-optimization and makes it more readable, so let us
do that.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14456
2023-02-06 11:09:28 -08:00
Richard Yao 3a7d2a0ce0 zfs_get_temporary_prop() should not pass NULL to strcpy()
`dsl_dir_activity_in_progress()` can call `zfs_get_temporary_prop()` with
the forth value set to NULL, which will pass NULL to `strcpy()` when
there is a match

Clang's static analyzer caught this with the help of CodeChecker for
Cross Translation Unit analysis.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14456
2023-02-06 11:08:57 -08:00
Matthew Ahrens 14872aaa4f
EIO caused by encryption + recursive gang
Encrypted blocks can not have 3 DVAs, because they use the space of the
3rd DVA for the IV+salt.  zio_write_gang_block() takes this into
account, setting `gbh_copies` to no more than 2 in this case.  Gang
members BP's do not have the X (encrypted) bit set (nor do they have the
DMU level and type fields set), because encryption is not handled at
this level.  The gang block is reassembled, and then encryption (and
compression) are handled.

To check if this gang block is encrypted, the code in
zio_write_gang_block() checks `pio->io_bp`.  This is normally fine,
because the block that's being ganged is typically the encrypted BP.

The problem is that if there is "recursive ganging", where a gang member
is itself a gang block, then when zio_write_gang_block() is called to
create a gang block for a gang member, `pio->io_bp` is the gang member's
BP, which doesn't have the X bit set, so the number of DVA's is not
restricted to 2.  It should instead be looking at the the "gang leader",
i.e. the top-level gang block, to determine how many DVA's can be used,
to avoid a "NDVA's inversion" (where a child has more DVA's than its
parent).

gang leader BP: X (encrypted) bit set, 2 DVA's, IV+salt in 3rd DVA's
space:
```
DVA[0]=<1:...:100400> DVA[1]=<0:...:100400> salt=... iv=...
[L0 ZFS plain file] fletcher4 uncompressed encrypted LE
gang unique double size=100000L/100000P birth=... fill=1 cksum=...
```

leader's GBH contains a BP with gang bit set and 3 DVA's:
```
DVA[0]=<1:...:55600> DVA[1]=<0:...:55600>
[L0 unallocated] fletcher4 uncompressed unencrypted LE
contiguous unique double size=55600L/55600P birth=... fill=0 cksum=...

DVA[0]=<1:...:55600> DVA[1]=<0:...:55600>
[L0 unallocated] fletcher4 uncompressed unencrypted LE
contiguous unique double size=55600L/55600P birth=... fill=0 cksum=...

DVA[0]=<1:...:55600> DVA[1]=<0:...:55600> DVA[2]=<1:...:200>
[L0 unallocated] fletcher4 uncompressed unencrypted LE
gang unique double size=55400L/55400P birth=... fill=0 cksum=...
```

On nondebug bits, having the 3rd DVA in the gang block works for the
most part, because it's true that all 3 DVA's are available in the gang
member BP (in the GBH).  However, for accounting purposes, gang block
DVA's ASIZE include all the space allocated below them, i.e. the
512-byte gang block header (GBH) as well as the gang members below that.
We see that above where the gang leader BP is 1MB logical (and after
compression: 0x`100000P`), but the ASIZE of each DVA is 2 sectors (1KB)
more than 1MB (0x`100400`).

Since thre are 3 copies of a block below it, we increment the ATIME of
the 3rd DVA of the gang leader by the space used by the 3rd DVA of the
child (1 sector, in this case).  But there isn't really a 3rd DVA of the
parent; the salt is stored in place of the 3rd DVA's ASIZE.

So when zio_write_gang_member_ready() increments the parent's BP's
`DVA[2]`'s ASIZE, it's actually incrementing the parent's salt.  When we
later try to read the encrypted recursively-ganged block, the salt
doesn't match what we used to write it, so MAC verification fails and we
get an EIO.

```
zio_encrypt():  encrypted 515/2/0/403 salt: 25 25 bb 9d ad d6 cd 89
zio_decrypt(): decrypting 515/2/0/403 salt: 26 25 bb 9d ad d6 cd 89
```

This commit addresses the problem by not increasing the number of copies
of the GBH beyond 2 (even for non-encrypted blocks).  This simplifies
the logic while maintaining the ability to traverse all metadata
(including gang blocks) even if one copy is lost.  (Note that 3 copies
of the GBH will still be created if requested, e.g. for `copies=3` or
MOS blocks.)  Additionally, the code that increments the parent's DVA's
ASIZE is made to check the parent DVA's NDVAS even on nondebug bits.  So
if there's a similar bug in the future, it will cause a panic when
trying to write, rather than corrupting the parent BP and causing an
error when reading.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Caused-by: #14356
Closes #14440
Closes #14413
2023-02-06 09:37:06 -08:00
Jorgen Lundman dffd40b3b6
Unify assembly files with macOS
The remaining changes needed to make the assembly files work
with macOS.

Reviewed-by: Attila Fülöp <attila@fueloep.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes #14451
2023-02-06 09:27:55 -08:00
Allan Jude c799866b97
Resolve WS-2021-0184 vulnerability in zstd
Pull in d40f55cd950919d7eac951b122668e55e33e5202 from upstream

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Allan Jude <allan@klarasystems.com>
Closes #14439
2023-02-02 15:12:51 -08:00
Brian Behlendorf 973934b965 Increase default zfs_rebuild_vdev_limit to 64MB
When testing distributed rebuild performance with more capable
hardware it was observed than increasing the zfs_rebuild_vdev_limit
to 64M reduced the rebuild time by 17%.  Beyond 64MB there was
some improvement (~2%) but it was not significant when weighed
against the increased memory usage. Memory usage is capped at 1/4
of arc_c_max.

Additionally, vr_bytes_inflight_max has been moved so it's updated
per-metaslab to allow the size to be adjust while a rebuild is
running.

Reviewed-by: Akash B <akash-b@hpe.com>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #14428
2023-01-27 10:02:24 -08:00
Brian Behlendorf c0aea7cf4e Increase default zfs_scan_vdev_limit to 16MB
For HDD based pools the default zfs_scan_vdev_limit of 4M
per-vdev can significantly limit the maximum scrub performance.
Increasing the default to 16M can double the scrub speed from
80 MB/s per disk to 160 MB/s per disk.

This does increase the memory footprint during scrub/resilver
but given the performance win this is a reasonable trade off.
Memory usage is capped at 1/4 of arc_c_max.  Note that number
of outstanding I/Os has not changed and is still limited by
zfs_vdev_scrub_max_active.

Reviewed-by: Akash B <akash-b@hpe.com>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #14428
2023-01-27 10:01:13 -08:00
Alexander Motin dc5c8006f6
Prefetch on deadlists merge
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Issue #14276 
Closes #14402
2023-01-25 11:30:24 -08:00
Brian Behlendorf c85ac731a0
Improve resilver ETAs
When resilvering the estimated time remaining is calculated using
the average issue rate over the current pass.  Where the current
pass starts when a scan was started, or restarted, if the pool
was exported/imported.

For dRAID pools in particular this can result in wildly optimistic
estimates since the issue rate will be very high while scanning
when non-degraded regions of the pool are scanned.  Once repair
I/O starts being issued performance drops to a realistic number
but the estimated performance is still significantly skewed.

To address this we redefine a pass such that it starts after a
scanning phase completes so the issue rate is more reflective of
recent performance.  Additionally, the zfs_scan_report_txgs
module option can be set to reset the pass statistics more often.

Reviewed-by: Akash B <akash-b@hpe.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #14410
2023-01-25 11:28:54 -08:00
Coleman Kane 9cd71c8604
linux 6.2 compat: zpl_set_acl arg2 is now struct dentry
Linux 6.2 changes the second argument of the set_acl operation to be a
"struct dentry *" rather than a "struct inode *". The inode* parameter
is still available as dentry->d_inode, so adjust the call to the _impl
function call to dereference and pass that pointer to it.

Also document that the get_acl -> get_inode_acl member name change from
commit 884a693 was an API change also introduced in Linux 6.2.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #14415
2023-01-24 11:20:50 -08:00
Alexander Motin 0f740a4f1d
Introduce minimal ZIL block commit delay
Despite all optimizations, tests on actual hardware show that FreeBSD
kernel can't sleep for less then ~2us.  Similar tests on Linux show
~50us delay at least from nanosleep() (haven't tested inside kernel).
It means that on very fast log device ZIL may not be able to satisfy
zfs_commit_timeout_pct block commit timeout, increasing log latency
more than desired.

Handle that by introduction of zil_min_commit_timeout parameter,
specifying minimal timeout value where additional delays to aggregate
writes may be skipped.  Also skip delays if the LWB is more than 7/8
full, that often happens if I/O sizes are constant and match one of
LWB sizes.  Both things are applied only if there were no already
outstanding log blocks, that may indicate single-threaded workload,
that by definition can not benefit from the commit delays.

While there, add short time moving average to zl_last_lwb_latency to
make it more stable.

Tests of single-threaded 4KB writes to NVDIMM SLOG on FreeBSD show IOPS
increase by 9% instead of expected 5%.  For zfs_commit_timeout_pct of
1 there IOPS increase by 5.5% instead of expected 1%.

Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #14418
2023-01-24 09:20:32 -08:00
Attila Fülöp 037e4f2536 x86 asm: Replace .align with .balign
The .align directive used to align storage locations is
ambiguous. On some platforms and assemblers it takes a byte count,
on others the argument is interpreted as a shift value. The current
usage expects the first interpretation.

Replace it with the unambiguous .balign directive which always
expects a byte count, regardless of platform and assembler.

Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes #14422
2023-01-24 09:04:39 -08:00
Attila Fülöp 58ca7b1011 IPC: blake3 x86 asm: fix placement of .size directives
The .size directive used by the SET_SIZE C macro uses the special
dot symbol to calculate the size of a function. The dot symbol
refers to the current address, so for the calculation to be
meaningful the SET_SIZE macro must be placed immediately after the
end of the function the size is calculated for.

Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes #14422
2023-01-24 09:03:31 -08:00
David Hedberg 37a27b4306
Wait for txg sync if the last DRR_FREEOBJECTS might result in a hole
If we receive a DRR_FREEOBJECTS as the first entry in an object range,
this might end up producing a hole if the freed objects were the
only existing objects in the block.

If the txg starts syncing before we've processed any following
DRR_OBJECT records, this leads to a possible race where the backing
arc_buf_t gets its psize set to 0 in the arc_write_ready() callback
while still being referenced from a dirty record in the open txg.

To prevent this, we insert a txg_wait_synced call if the first
record in the range was a DRR_FREEOBJECTS that actually
resulted in one or more freed objects.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: David Hedberg <david.hedberg@findity.com>
Sponsored by: Findity AB
Closes #11893
Closes #14358
2023-01-23 13:19:43 -08:00
Richard Yao 73968defdd
Reject streams that set ->drr_payloadlen to unreasonably large values
In the zstream code, Coverity reported:

"The argument could be controlled by an attacker, who could invoke the
function with arbitrary values (for example, a very high or negative
buffer size)."

It did not report this in the kernel. This is likely because the
userspace code stored this in an int before passing it into the
allocator, while the kernel code stored it in a uint32_t.

However, this did reveal a potentially real problem. On 32-bit systems
and systems with only 4GB of physical memory or less in general, it is
possible to pass a large enough value that the system will hang. Even
worse, on Linux systems, the kernel memory allocator is not able to
support allocations up to the maximum 4GB allocation size that this
allows.

This had already been limited in userspace to 64MB by
`ZFS_SENDRECV_MAX_NVLIST`, but we need a hard limit in the kernel to
protect systems. After some discussion, we settle on 256MB as a hard
upper limit. Attempting to receive a stream that requires more memory
than that will result in E2BIG being returned to user space.

Reported-by: Coverity (CID-1529836)
Reported-by: Coverity (CID-1529837)
Reported-by: Coverity (CID-1529838)
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14285
2023-01-23 13:16:22 -08:00
rob-wing 69f024a56e
Configure zed's diagnosis engine with vdev properties
Introduce four new vdev properties:
    checksum_n
    checksum_t
    io_n
    io_t

These properties can be used for configuring the thresholds of zed's
diagnosis engine and are interpeted as <N> events in T <seconds>.

When this property is set to a non-default value on a top-level vdev,
those thresholds will also apply to its leaf vdevs. This behavior can be
overridden by explicitly setting the property on the leaf vdev.

Note that, these properties do not persist across vdev replacement. For
this reason, it is advisable to set the property on the top-level vdev
instead of the leaf vdev.

The default values for zed's diagnosis engine (10 events, 600 seconds)
remains unchanged.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Rob Wing <rob.wing@klarasystems.com>
Sponsored-by: Seagate Technology LLC
Closes #13805
2023-01-23 13:14:25 -08:00
Richard Yao f091db9248
free_blocks(): Fix reports from 2016 PVS Studio FreeBSD report
In 2016, the authors of PVS Studio ran it on the FreeBSD kernel, which
identified a number of bugs / cleanup opportunities in the FreeBSD ZFS kernel
code. A few of them persist to the present day:

https://reviews.freebsd.org/D5245

Note that the scan was done against
freebsd/freebsd-src@46763fd4ca.

In particular, we have the following in free_blocks():

\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\dnode_sync.c (174): error V547: Expression '__left >= __right' is always true. Unsigned type value is always >= 0.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\dnode_sync.c (171): error V634: The priority of the '*' operation is higher than that of the '<<' operation. It's possible that parentheses should be used in the expression.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\dnode_sync.c (175): error V547: Expression '__left >= __right' is always true. Unsigned type value is always >= 0.

A couple of assertions accidentally typecast the arguments they check to
unsigned in such a way that the result is always true. Also, parentheses
are missing around `1<<epbs` in `(db->db_blkid * 1<<epbs)`. This works
out to be okay due to multiplication not caring what order of operations
we use, but it is better to fix it to be `(db->db_blkid << epbs)`.

A few of the function local variables probably never should have been
32-bit in the first place, so we make them 64-bit. We also replace the
existing assertions with additional assertions to ensure that 64-bit
unsigned arithmetic is safe.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14407
2023-01-23 13:12:37 -08:00
Chunwei Chen 71974946be
Fix reading uninitialized variable in receive_read
When zfs_file_read returns error, resid may be uninitialized.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Chunwei Chen <david.chen@nutanix.com>
Closes #14404
2023-01-20 11:49:56 -08:00
Richard Yao 856cefcd1c
Cleanup ->dd_space_towrite should be unsigned
This is only ever used with unsigned data, so the type itself should be
unsigned. Also, PVS Studio's 2016 FreeBSD kernel report correctly
identified the following assertion as always being true, so we can drop
it:

ASSERT3U(dd->dd_space_towrite[i & TXG_MASK], >=, 0);

The reason it was always true is because it would do casts to give us
unsigned comparisons. This could have been fixed by switching to
`ASSERT3S()`, but upon inspection, it turned out that this variable
never should have been allowed to be signed in the first place.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14408
2023-01-20 11:10:15 -08:00
Mark Johnston ebabb93e6c Micro-optimize dsl_prop_get_dd()
Use the saved property index instead of looking it up once per DSL
directory when traversing up towards the root.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Akash B <akash-b@hpe.com>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Sponsored-by: The FreeBSD Foundation
Closes #14397
2023-01-20 11:01:41 -08:00
Mark Johnston 7c30100c00 Avoid passing an uninitialized index to dsl_prop_known_index
Reported-by: KMSAN
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Akash B <akash-b@hpe.com>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Sponsored-by: The FreeBSD Foundation
Closes #14397
2023-01-20 11:00:38 -08:00
Chunwei Chen c6dab6dd39
Fix unprotected zfs_znode_dmu_fini
In original code, zfs_znode_dmu_fini is called in zfs_rmnode without
zfs_znode_hold_enter. It seems to assume it's ok to do so when the znode
is unlinked. However this assumption is not correct, as zfs_zget can be
called by NFS through zpl_fh_to_dentry as pointed out by Christian in
https://github.com/openzfs/zfs/pull/12767, which could result in a
use-after-free bug.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Chunwei Chen <david.chen@nutanix.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #12767 
Closes #14364
2023-01-19 16:59:05 -08:00
Jorgen Lundman 68c0771cc9
Unify Assembler files between Linux and Windows
Add new macro ASMABI used by Windows to change
calling API to "sysv_abi".

Reviewed-by: Attila Fülöp <attila@fueloep.org>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes #14228
2023-01-17 11:09:19 -08:00
Richard Yao 2e7f664f04
Cleanup of dead code suggested by Clang Static Analyzer (#14380)
I recently gained the ability to run Clang's static analyzer on the
linux kernel modules via a few hacks. This extended coverage to code
that was previously missed since Clang's static analyzer only looked at
code that we built in userspace. Running it against the Linux kernel
modules built from my local branch produced a total of 72 reports
against my local branch. Of those, 50 were reports of logic errors and
22 were reports of dead code. Since we already had cleaned up all of
the previous dead code reports, I felt it would be a good next step to
clean up these dead code reports. Clang did a further breakdown of the
dead code reports into:

Dead assignment	15

Dead increment	2

Dead nested assignment	5

The benefit of cleaning these up, especially in the case of dead nested
assignment, is that they can expose places where our error handling is
incorrect. A number of them were fairly straight forward. However
several were not:

In vdev_disk_physio_completion(), not only were we not using the return
value from the static function vdev_disk_dio_put(), but nothing used it,
so I changed it to return void and removed the existing (void) cast in
the other area where we call it in addition to no longer storing it to a
stack value.

In FSE_createDTable(), the function is dead code. Its helper function
FSE_freeDTable() is also dead code, as are the CPP definitions in
`module/zstd/include/zstd_compat_wrapper.h`. We just delete it all.

In zfs_zevent_wait(), we have an optimization opportunity. cv_wait_sig()
returns 0 if there are waiting signals and 1 if there are none. The
Linux SPL version literally returns `signal_pending(current) ? 0 : 1)`
and FreeBSD implements the same semantics, we can just do
`!cv_wait_sig()` in place of `signal_pending(current)` to avoid
unnecessarily calling it again.

zfs_setattr() on FreeBSD version did not have error handling issue
because the code was removed entirely from FreeBSD version. The error is
from updating the attribute directory's files. After some thought, I
decided to propapage errors on it to userspace.

In zfs_secpolicy_tmp_snapshot(), we ignore a lack of permission from the
first check in favor of checking three other permissions. I assume this
is intentional.

In zfs_create_fs(), the return value of zap_update() was not checked
despite setting an important version number. I see no backward
compatibility reason to permit failures, so we add an assertion to catch
failures. Interestingly, Linux is still using ASSERT(error == 0) from
OpenSolaris while FreeBSD has switched to the improved ASSERT0(error)
from illumos, although illumos has yet to adopt it here. ASSERT(error ==
0) was used on Linux while ASSERT0(error) was used on FreeBSD since the
entire file needs conversion and that should be the subject of
another patch.

dnode_move()'s issue was caused by us not having implemented
POINTER_IS_VALID() on Linux. We have a stub in
`include/os/linux/spl/sys/kmem_cache.h` for it, when it really should be
in `include/os/linux/spl/sys/kmem.h` to be consistent with
Illumos/OpenSolaris. FreeBSD put both `POINTER_IS_VALID()` and
`POINTER_INVALIDATE()` in `include/os/freebsd/spl/sys/kmem.h`, so we
copy what it did.

Whenever a report was in platform-specific code, I checked the FreeBSD
version to see if it also applied to FreeBSD, but it was only relevant a
few times.

Lastly, the patch that enabled Clang's static analyzer to be run on the
Linux kernel modules needs more work before it can be put into a PR. I
plan to do that in the future as part of the on-going static analysis
work that I am doing.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14380
2023-01-17 09:57:12 -08:00
Richard Yao d27c7ba62f
Linux ppc64le ieee128 compat: Do not redefine __asm on external headers
There is an external assembly declaration extension in GNU C that glibc
uses when building with ieee128 floating point support on ppc64le.
Marking that as volatile makes no sense, so the build breaks.

It does not make sense to only mark this as volatile on Linux, since if
do not want the compiler reordering things on Linux, we do not want the
compiler reordering things on any other platform, so we stop treating
Linux specially and just manually inline the CPP macro so that we can
eliminate it. This should fix the build on ppc64le.

Tested-by: @gyakovlev 
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14308
Closes #14384
2023-01-13 10:58:58 -08:00
Richard Yao 4ef69de384 Cleanup: Use NULL when doing NULL pointer comparisons
The Linux 5.16.14 kernel's coccicheck caught this. The semantic
patch that caught it was:

./scripts/coccinelle/null/badzero.cocci

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 16:00:37 -08:00
Richard Yao 64195fc89f Cleanup: Remove unneeded semicolons
The Linux 5.16.14 kernel's coccicheck caught this. The semantic
patch that caught it was:

./scripts/coccinelle/misc/semicolon.cocci

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 16:00:30 -08:00
Richard Yao 3b2f9c1ec8 Cleanup: Use MIN() macro
The Linux 5.16.14 kernel's coccicheck caught this. The semantic
patch that caught it was:

./scripts/coccinelle/misc/minmax.cocci

There was a third opportunity to use `MIN()`, but that was in
`FSE_minTableLog()` in `module/zstd/lib/compress/fse_compress.c`.
Upstream zstd has yet to make this change and I did not want to change
header includes just for MIN, or do a one off, so I left it alone.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 16:00:23 -08:00
Richard Yao e6328fda2e Cleanup: !A || A && B is equivalent to !A || B
In zfs_zaccess_dataset_check(), we have the following subexpression:

(!IS_DEVVP(ZTOV(zp)) ||
    (IS_DEVVP(ZTOV(zp)) && (v4_mode & WRITE_MASK_ATTRS)))

When !IS_DEVVP(ZTOV(zp)) is false, IS_DEVVP(ZTOV(zp)) is true under the
law of the excluded middle since we are not doing pseudoboolean alegbra.
Therefore doing:

(IS_DEVVP(ZTOV(zp)) && (v4_mode & WRITE_MASK_ATTRS))

Is unnecessary and we can just do:

(v4_mode & WRITE_MASK_ATTRS)

The Linux 5.16.14 kernel's coccicheck caught this. The semantic
patch that caught it was:

./scripts/coccinelle/misc/excluded_middle.cocci

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 16:00:15 -08:00
Richard Yao 9c8fabffa2 Cleanup: Replace oldstyle struct hack with C99 flexible array members
The Linux 5.16.14 kernel's coccicheck caught this. The semantic
patch that caught it was:

./scripts/coccinelle/misc/flexible_array.cocci

However, unlike the cases where the GNU zero length array extension had
been used, coccicheck would not suggest patches for the older style
single member arrays. That was good because blindly changing them would
break size calculations in most cases.

Therefore, this required care to make sure that we did not break size
calculations. In the case of `indirect_split_t`, we use
`offsetof(indirect_split_t, is_child[is->is_children])` to calculate
size. This might be subtly wrong according to an old mailing list
thread:

https://inbox.sourceware.org/gcc-prs/20021226123454.27019.qmail@sources.redhat.com/T/

That is because the C99 specification should consider the flexible array
members to start at the end of a structure, but compilers prefer to put
padding at the end. A suggestion was made to allow compilers to allocate
padding after the VLA like compilers already did:

http://std.dkuug.dk/JTC1/SC22/WG14/www/docs/n983.htm

However, upon thinking about it, whether or not we allocate end of
structure padding does not matter, so using offsetof() to calculate the
size of the structure is fine, so long as we do not mix it with sizeof()
on structures with no array members.

In the case that we mix them and padding causes offsetof(struct_t,
vla_member[0]) to differ from sizeof(struct_t), we would be doing unsafe
operations if we underallocate via `offsetof()` and then overcopy via
sizeof().

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 16:00:03 -08:00
Richard Yao d35ccc1f59 Cleanup: Fix indentation in zfs_dbgmsg_t
fdc2d30371 accidentally broke the
indentation.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 15:59:56 -08:00
Richard Yao 8e7ebf4e2d Cleanup: Use C99 flexible array members instead of zero length arrays
The Linux 5.16.14 kernel's coccicheck caught this. The semantic
patch that caught it was:

./scripts/coccinelle/misc/flexible_array.cocci

The Linux kernel's documentation makes a good case for why we should not
use these:

https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 15:59:41 -08:00
Richard Yao c9c3ce7976 Cleanup: Use kmem_zalloc() instead of memset() to zero memory
The Linux 5.16.14 kernel's coccicheck caught this. The semantic patch
that caught it was:

./scripts/coccinelle/api/alloc/zalloc-simple.cocci

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 15:59:28 -08:00
Richard Yao 7384ec65cd Cleanup: Remove unnecessary explicit casts of pointers from allocators
The Linux 5.16.14 kernel's coccicheck caught these. The semantic patch
that caught them was:

./scripts/coccinelle/api/alloc/alloc_cast.cocci

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14372
2023-01-12 15:59:12 -08:00
George Amanakis eee9362a72
Activate filesystem features only in syncing context
When activating filesystem features after receiving a snapshot, do 
so only in syncing context.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #14304 
Closes #14252
2023-01-11 18:00:39 -08:00
Mateusz Piotrowski 926715b9fc
Turn default_bs and default_ibs into ZFS_MODULE_PARAMs
The default_bs and default_ibs tunables control the default block size
and indirect block size.

So far, default_bs and default_ibs were tunable only on FreeBSD, e.g.,

    sysctl vfs.zfs.default_ibs

Remove the FreeBSD-specific sysctl code and expose default_bs and
default_ibs as tunables on both Linux and FreeBSD using
ZFS_MODULE_PARAM.

One of the use cases for changing the values of those tunables is to
lower the indirect block size, which may improve performance of large
directories (as discussed during the OpenZFS Leadership Meeting
on 2022-08-16).

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Mateusz Piotrowski <mateusz.piotrowski@klarasystems.com>
Sponsored-by: Wasabi Technology, Inc.
Closes #14293
2023-01-11 09:38:20 -08:00
Mateusz Piotrowski a4b21eadec
Add tunable to allow changing micro ZAP's max size
This change turns `MZAP_MAX_BLKSZ` into a `ZFS_MODULE_PARAM()` called
`zap_micro_max_size`. As a result, we can experiment with different
micro ZAP sizes to improve directory size scaling.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Mateusz Piotrowski <mateuszpiotrowski@klarasystems.com>
Co-authored-by: Toomas Soome <toomas.soome@klarasystems.com>
Signed-off-by: Mateusz Piotrowski <mateuszpiotrowski@klarasystems.com>
Sponsored-by: Wasabi Technology, Inc.
Closes #14292
2023-01-10 13:41:54 -08:00
Matthew Ahrens fc45975ec8
Batch enqueue/dequeue for bqueue
The Blocking Queue (bqueue) code is used by zfs send/receive to send
messages between the various threads.  It uses a shared linked list,
which is locked whenever we enqueue or dequeue.  For workloads which
process many blocks per second, the locking on the shared list can be
quite expensive.

This commit changes the bqueue logic to have 3 linked lists:
1. An enquing list, which is used only by the (single) enquing thread,
   and thus needs no locks.
2. A shared list, with an associated lock.
3. A dequing list, which is used only by the (single) dequing thread,
   and thus needs no locks.

The entire enquing list can be moved to the shared list in constant
time, and the entire shared list can be moved to the dequing list in
constant time.  These operations only happen when the `fill_fraction` is
reached, or on an explicit flush request.  Therefore, the lock only
needs to be acquired infrequently.

The API already allows for dequing to block until an explicit flush, so
callers don't need to be changed.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #14121
2023-01-10 13:39:22 -08:00
Brian Behlendorf 0c8fbe5b6a ztest: update ztest_dmu_snapshot_create_destroy()
ECHRNG is returned when the channel program encounters a runtime
error.  For example, this can happen when a snapshot doesn't exist.
We handle this error the same way as the existing EEXIST and ENOENT
error checks.

Additionally, improve the internal debug message to include the
error describing why a pool couldn't be opened.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #14351
2023-01-10 13:27:48 -08:00
Matthew Ahrens 40d7e971ff
ztest fails assertion in zio_write_gang_member_ready()
Encrypted blocks can have up to 2 DVA's, as the third DVA is reserved
for the salt+IV.  However, dmu_write_policy() allows non-encrypted
blocks (e.g. DMU_OT_OBJSET) inside encrypted datasets to request and
allocate 3 DVA's, since they don't need a salt+IV (they are merely
authenicated).

However, if such a block becomes a gang block, the gang code incorrectly
limits the gang block header to 2 DVA's.  This leads to a "NDVAs
inversion", where a parent block (the gang block header) has less DVA's
than its children (the gang members), causing an assertion failure in
zio_write_gang_member_ready().

This commit addresses the problem by only restricting the gang block
header to 2 DVA's if the block is actually encrypted (and thus its gang
block members can have at most 2 DVA's).

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #14250
Closes #14356
2023-01-09 16:43:45 -08:00
Ameer Hamza 5091867ee6
zed: add hotplug support for spare vdevs
This commit supports for spare vdev hotplug. The
spare vdev associated with all the pools will be
marked as "Removed" when the drive is physically
detached and will become "Available" when the
drive is reattached. Currently, the spare vdev
status does not change on the drive removal and
the same is the case with reattachment.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>
Closes #14295
2023-01-09 12:43:03 -08:00
Alexander Motin 289f7e6adb
Remove some dead ARC code. (#14340)
Every ARC buffer holds a reference on the header. It means headers with
buffers are never evictable.  When we are evicting a header, there can
be no more buffers to free.  Just assert that.

b_evict_lock seems not protecting anything now.  Remove it.

Buffers checksum should also be freed with the last uncompressed buffer,
so it should not be there also when we are evicting the header.

Signed-off-by:  Alexander Motin <mav@FreeBSD.org>
Sponsored by:   iXsystems, Inc.
2023-01-09 10:45:17 -08:00
Coleman Kane 884a69357f linux 6.2 compat: get_acl() got moved to get_inode_acl() in 6.2
Linux 6.2 renamed the get_acl() operation to get_inode_acl() in
the inode_operations struct. This should fix Issue #14323.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #14323
Closes #14331
2023-01-06 14:40:54 -08:00
Antonio Russo d27c81847b Linux 6.1 compat: open inside tmpfile()
Linux 863f144 modified the .tmpfile interface to pass a struct file,
rather than a struct dentry, and expect the tmpfile implementation to
open inside of tmpfile().

This patch implements a configuration test that checks for this new API
and appropriately sets a HAVE_TMPFILE_DENTRY flag that tracks this old
API.  Contingent on this flag, the appropriate API is implemented.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Antonio Russo <aerusso@aerusso.net>
Closes #14301
Closes #14343
2023-01-06 14:33:00 -08:00
Richard Yao 1f3bc5ea80
Illumos #15286: do_composition() needs sign awareness
Authored by: Dan McDonald <danmcd@mnx.io>
Reviewed by: Patrick Mooney <pmooney@pfmooney.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Approved by: Joshua M. Clulow <josh@sysmgr.org>
Ported-by: Richard Yao <richard.yao@alumni.stonybrook.edu>

Illumos-issue: https://www.illumos.org/issues/15286
Illumos-commit: f137b22e73

Porting Notes:

The patch in illumos did not have much of a commit message, and did not
provide attribution to the reporter, while original patch proposed to
OpenZFS did, so I am listing the reporter (myself) and original patch
author (also myself) below while including the original commit message
with some minor corrections as part of the porting notes:

In do_composition(), we have:

size = u8_number_of_bytes[*p];
if (size <= 1 || (p + size) > oslast)
	break;

There, we have type promotion from int8_t to size_t, which is unsigned.
C will sign extend the value as part of the widening before treating the
value as unsigned and the negative values we can counter are error
values from U8_ILLEGAL_CHAR and U8_OUT_OF_RANGE_CHAR, which are -1 and
-2 respectively. The unsigned versions of these under two's complement
are SIZE_MAX and SIZE_MAX-1 respectively.

The bounds check is written under the assumption that `size <= 1` does a
signed comparison. This is followed by a pointer comparison to see if
the string has the correct length, which is fine.

A little further down we have:

for (i = 0; i < size; i++)
	tc[i] = *p++;

When an error condition is encountered, this will attempt to iterate at
least SIZE_MAX-1 times, which will massively overflow the buffer, which
is not fine.

The kernel will kill the loop as soon as it hits the kernel stack guard
on Linux systems built with CONFIG_VMAP_STACK=y, which should be just
about all of them. That prevents arbitrary code execution and just about
any other bad thing that a black hat attacker might attempt with
knowledge of this buffer overflow. Other systems' kernels have
mitigations for unbounded in-kernel buffer overflows that will catch
this too.

Also, the patch in illumos-gate made an effort to fix C style issues
that had been fixed in the OpenZFS/ZFSOnLinux repository. Those issues
had been mentioned in the email that I originally sent them about this
issue. One of the fixes had not been already done, so it is included.
Another to collect_a_seq()'s arguments was handled differently in
OpenZFS. For the sake of avoiding unnecessary differences, it has been
adopted. This has the interesting effect that if you correct the paths
in the illumos-gate patch to match the current OpenZFS repository, you
can reverse apply it cleanly.

Original-patch-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reported-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Co-authored-by: Dan McDonald <danmcd@mnx.io>
Closes #14318
Closes #14342
2023-01-05 11:16:21 -08:00
Mateusz Guzik f25f1f9091
FreeBSD: catch up to 1400077
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Closes #14328
2023-01-05 10:56:40 -08:00