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Cleanup dump_bookmarks() 

Assertions are meant to check assumptions, but the way that this
assertion is written does not check an assumption, since it is provably
always true. Removing the assertion will cause a compiler warning (made
into an error by -Werror) about printing up to 512 bytes to a 256-byte
buffer, so instead, we change the assertion to verify the assumption
that we never do a snprintf() that is truncated to avoid overrunning the
256-byte buffer.

This was caught by an audit of the codebase to look for misuse of
`snprintf()` after CodeQL reported that we had misused `snprintf()`. An
explanation of how snprintf() can be misused is here:

https://www.redhat.com/en/blog/trouble-snprintf

This particular instance did not misuse `snprintf()`, but it was caught
by the audit anyway.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14098
This commit is contained in:
Richard Yao 2022-10-27 15:41:39 -04:00 committed by Brian Behlendorf
parent d71d693261
commit 2e08df84d8
1 changed files with 4 additions and 2 deletions
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6
cmd/zdb/zdb.c
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@ -2858,9 +2858,11 @@ dump_bookmarks(objset_t *os, int verbosity)
zap_cursor_advance(&zc)) {
char osname[ZFS_MAX_DATASET_NAME_LEN];
char buf[ZFS_MAX_DATASET_NAME_LEN];
int len;
dmu_objset_name(os, osname);
VERIFY3S(0, <=, snprintf(buf, sizeof (buf), "%s#%s", osname,
attr.za_name));
len = snprintf(buf, sizeof (buf), "%s#%s", osname,
attr.za_name);
VERIFY3S(len, <, ZFS_MAX_DATASET_NAME_LEN);
(void) dump_bookmark(dp, buf, verbosity >= 5, verbosity >= 6);
}
zap_cursor_fini(&zc);