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authorFeng Tang <feng.tang@intel.com>2022-09-19 11:12:41 +0800
committerVlastimil Babka <vbabka@suse.cz>2022-09-19 16:27:26 +0200
commitd71608a877362becdc94191f190902fac1e64d35 (patch)
tree708e8d4f060d3a5e4374e52dec6ea3d1eefc80c6 /mm
parent5373b8a09d6e037ee0587cb5d9fe4cc09077deeb (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')
-rw-r--r--mm/slab_common.c5
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);