diff options
| author | Feng Tang <feng.tang@intel.com> | 2022-09-19 11:12:41 +0800 |
|---|---|---|
| committer | Vlastimil Babka <vbabka@suse.cz> | 2022-09-19 16:27:26 +0200 |
| commit | d71608a877362becdc94191f190902fac1e64d35 (patch) | |
| tree | 708e8d4f060d3a5e4374e52dec6ea3d1eefc80c6 /mm/slab_common.c | |
| parent | 5373b8a09d6e037ee0587cb5d9fe4cc09077deeb (diff) | |
mm/slab_common: fix possible double free of kmem_cache
When doing slub_debug test, kfence's 'test_memcache_typesafe_by_rcu'
kunit test case cause a use-after-free error:
BUG: KASAN: use-after-free in kobject_del+0x14/0x30
Read of size 8 at addr ffff888007679090 by task kunit_try_catch/261
CPU: 1 PID: 261 Comm: kunit_try_catch Tainted: G B N 6.0.0-rc5-next-20220916 #17
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x48
print_address_description.constprop.0+0x87/0x2a5
print_report+0x103/0x1ed
kasan_report+0xb7/0x140
kobject_del+0x14/0x30
kmem_cache_destroy+0x130/0x170
test_exit+0x1a/0x30
kunit_try_run_case+0xad/0xc0
kunit_generic_run_threadfn_adapter+0x26/0x50
kthread+0x17b/0x1b0
</TASK>
The cause is inside kmem_cache_destroy():
kmem_cache_destroy
acquire lock/mutex
shutdown_cache
schedule_work(kmem_cache_release) (if RCU flag set)
release lock/mutex
kmem_cache_release (if RCU flag not set)
In some certain timing, the scheduled work could be run before
the next RCU flag checking, which can then get a wrong value
and lead to double kmem_cache_release().
Fix it by caching the RCU flag inside protected area, just like 'refcnt'
Fixes: 0495e337b703 ("mm/slab_common: Deleting kobject in kmem_cache_destroy() without holding slab_mutex/cpu_hotplug_lock")
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'mm/slab_common.c')
| -rw-r--r-- | mm/slab_common.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 07b948288f84..ccc02573588f 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -475,6 +475,7 @@ void slab_kmem_cache_release(struct kmem_cache *s) void kmem_cache_destroy(struct kmem_cache *s) { int refcnt; + bool rcu_set; if (unlikely(!s) || !kasan_check_byte(s)) return; @@ -482,6 +483,8 @@ void kmem_cache_destroy(struct kmem_cache *s) cpus_read_lock(); mutex_lock(&slab_mutex); + rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; + refcnt = --s->refcount; if (refcnt) goto out_unlock; @@ -492,7 +495,7 @@ void kmem_cache_destroy(struct kmem_cache *s) out_unlock: mutex_unlock(&slab_mutex); cpus_read_unlock(); - if (!refcnt && !(s->flags & SLAB_TYPESAFE_BY_RCU)) + if (!refcnt && !rcu_set) kmem_cache_release(s); } EXPORT_SYMBOL(kmem_cache_destroy); |