Illumos 5531 - NULL pointer dereference in dsl_prop_get_ds()

5531 NULL pointer dereference in dsl_prop_get_ds()
Author: Justin T. Gibbs <justing@spectralogic.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Robert Mustacchi <rm@joyent.com>

References:
  https://www.illumos.org/issues/5531
  https://github.com/illumos/illumos-gate/commit/e57a022

Ported-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Justin T. Gibbs 2015-04-02 22:59:15 +11:00 committed by Brian Behlendorf
parent 0c66c32d1d
commit 6ebebaceb1
7 changed files with 116 additions and 16 deletions

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@ -262,12 +262,15 @@ int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
void dbuf_prefetch(struct dnode *dn, uint64_t blkid, zio_priority_t prio);
void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
uint64_t blkid, void *tag);
uint64_t dbuf_refcount(dmu_buf_impl_t *db);
void dbuf_rele(dmu_buf_impl_t *db, void *tag);
void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
dmu_buf_impl_t *dbuf_find(struct dnode *dn, uint8_t level, uint64_t blkid);
dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
uint64_t blkid);
int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);

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@ -454,7 +454,23 @@ int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
*/
int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
void *tag, dmu_buf_t **, int flags);
/*
* Add a reference to a dmu buffer that has already been held via
* dmu_buf_hold() in the current context.
*/
void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
/*
* Attempt to add a reference to a dmu buffer that is in an unknown state,
* using a pointer that may have been invalidated by eviction processing.
* The request will succeed if the passed in dbuf still represents the
* same os/object/blkid, is ineligible for eviction, and has at least
* one hold by a user other than the syncer.
*/
boolean_t dmu_buf_try_add_ref(dmu_buf_t *, objset_t *os, uint64_t object,
uint64_t blkid, void *tag);
void dmu_buf_rele(dmu_buf_t *db, void *tag);
uint64_t dmu_buf_refcount(dmu_buf_t *db);

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@ -197,6 +197,8 @@ dsl_dataset_phys(dsl_dataset_t *ds)
int dsl_dataset_hold(struct dsl_pool *dp, const char *name, void *tag,
dsl_dataset_t **dsp);
boolean_t dsl_dataset_try_add_ref(struct dsl_pool *dp, dsl_dataset_t *ds,
void *tag);
int dsl_dataset_hold_obj(struct dsl_pool *dp, uint64_t dsobj, void *tag,
dsl_dataset_t **);
void dsl_dataset_rele(dsl_dataset_t *ds, void *tag);

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@ -149,16 +149,13 @@ dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
(dbuf)->db_blkid == (blkid))
dmu_buf_impl_t *
dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
dbuf_find(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid)
{
dbuf_hash_table_t *h = &dbuf_hash_table;
objset_t *os = dn->dn_objset;
uint64_t obj;
uint64_t hv;
uint64_t idx;
dmu_buf_impl_t *db;
obj = dn->dn_object;
hv = DBUF_HASH(os, obj, level, blkid);
idx = hv & h->hash_table_mask;
@ -177,6 +174,24 @@ dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
return (NULL);
}
static dmu_buf_impl_t *
dbuf_find_bonus(objset_t *os, uint64_t object)
{
dnode_t *dn;
dmu_buf_impl_t *db = NULL;
if (dnode_hold(os, object, FTAG, &dn) == 0) {
rw_enter(&dn->dn_struct_rwlock, RW_READER);
if (dn->dn_bonus != NULL) {
db = dn->dn_bonus;
mutex_enter(&db->db_mtx);
}
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, FTAG);
}
return (db);
}
/*
* Insert an entry into the hash table. If there is already an element
* equal to elem in the hash table, then the already existing element
@ -2000,7 +2015,7 @@ dbuf_prefetch(dnode_t *dn, uint64_t blkid, zio_priority_t prio)
return;
/* dbuf_find() returns with db_mtx held */
if ((db = dbuf_find(dn, 0, blkid))) {
if ((db = dbuf_find(dn->dn_objset, dn->dn_object, 0, blkid))) {
/*
* This dbuf is already in the cache. We assume that
* it is already CACHED, or else about to be either
@ -2048,7 +2063,8 @@ __dbuf_hold_impl(struct dbuf_hold_impl_data *dh)
*(dh->dh_dbp) = NULL;
top:
/* dbuf_find() returns with db_mtx held */
dh->dh_db = dbuf_find(dh->dh_dn, dh->dh_level, dh->dh_blkid);
dh->dh_db = dbuf_find(dh->dh_dn->dn_objset, dh->dh_dn->dn_object,
dh->dh_level, dh->dh_blkid);
if (dh->dh_db == NULL) {
dh->dh_bp = NULL;
@ -2228,6 +2244,30 @@ dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
VERIFY(refcount_add(&db->db_holds, tag) > 1);
}
#pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref
boolean_t
dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid,
void *tag)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dmu_buf_impl_t *found_db;
boolean_t result = B_FALSE;
if (db->db_blkid == DMU_BONUS_BLKID)
found_db = dbuf_find_bonus(os, obj);
else
found_db = dbuf_find(os, obj, 0, blkid);
if (found_db != NULL) {
if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) {
(void) refcount_add(&db->db_holds, tag);
result = B_TRUE;
}
mutex_exit(&db->db_mtx);
}
return (result);
}
/*
* If you call dbuf_rele() you had better not be referencing the dnode handle
* unless you have some other direct or indirect hold on the dnode. (An indirect

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@ -77,7 +77,8 @@ dnode_increase_indirection(dnode_t *dn, dmu_tx_t *tx)
/* set dbuf's parent pointers to new indirect buf */
for (i = 0; i < nblkptr; i++) {
dmu_buf_impl_t *child = dbuf_find(dn, old_toplvl, i);
dmu_buf_impl_t *child =
dbuf_find(dn->dn_objset, dn->dn_object, old_toplvl, i);
if (child == NULL)
continue;

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@ -351,6 +351,13 @@ dsl_dataset_snap_remove(dsl_dataset_t *ds, const char *name, dmu_tx_t *tx,
return (err);
}
boolean_t
dsl_dataset_try_add_ref(dsl_pool_t *dp, dsl_dataset_t *ds, void *tag)
{
return (dmu_buf_try_add_ref(ds->ds_dbuf, dp->dp_meta_objset,
ds->ds_object, DMU_BONUS_BLKID, tag));
}
int
dsl_dataset_hold_obj(dsl_pool_t *dp, uint64_t dsobj, void *tag,
dsl_dataset_t **dsp)

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@ -441,9 +441,31 @@ dsl_prop_notify_all_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
cbr = list_next(&dd->dd_prop_cbs, cbr)) {
uint64_t value;
/*
* Callback entries do not have holds on their datasets
* so that datasets with registered callbacks are still
* eligible for eviction. Unlike operations on callbacks
* for a single dataset, we are performing a recursive
* descent of related datasets and the calling context
* for this iteration only has a dataset hold on the root.
* Without a hold, the callback's pointer to the dataset
* could be invalidated by eviction at any time.
*
* Use dsl_dataset_try_add_ref() to verify that the
* dataset has not begun eviction processing and to
* prevent eviction from occurring for the duration
* of the callback. If the hold attempt fails, this
* object is already being evicted and the callback can
* be safely ignored.
*/
if (!dsl_dataset_try_add_ref(dp, cbr->cbr_ds, FTAG))
continue;
if (dsl_prop_get_ds(cbr->cbr_ds, cbr->cbr_propname,
sizeof (value), 1, &value, NULL) == 0)
cbr->cbr_func(cbr->cbr_arg, value);
dsl_dataset_rele(cbr->cbr_ds, FTAG);
}
mutex_exit(&dd->dd_lock);
@ -496,19 +518,28 @@ dsl_prop_changed_notify(dsl_pool_t *dp, uint64_t ddobj,
mutex_enter(&dd->dd_lock);
for (cbr = list_head(&dd->dd_prop_cbs); cbr;
cbr = list_next(&dd->dd_prop_cbs, cbr)) {
uint64_t propobj = dsl_dataset_phys(cbr->cbr_ds)->ds_props_obj;
if (strcmp(cbr->cbr_propname, propname) != 0)
continue;
uint64_t propobj;
/*
* If the property is set on this ds, then it is not
* inherited here; don't call the callback.
* cbr->cbf_ds may be invalidated due to eviction,
* requiring the use of dsl_dataset_try_add_ref().
* See comment block in dsl_prop_notify_all_cb()
* for details.
*/
if (propobj && 0 == zap_contains(mos, propobj, propname))
if (strcmp(cbr->cbr_propname, propname) != 0 ||
!dsl_dataset_try_add_ref(dp, cbr->cbr_ds, FTAG))
continue;
cbr->cbr_func(cbr->cbr_arg, value);
propobj = dsl_dataset_phys(cbr->cbr_ds)->ds_props_obj;
/*
* If the property is not set on this ds, then it is
* inherited here; call the callback.
*/
if (propobj == 0 || zap_contains(mos, propobj, propname) != 0)
cbr->cbr_func(cbr->cbr_arg, value);
dsl_dataset_rele(cbr->cbr_ds, FTAG);
}
mutex_exit(&dd->dd_lock);