diff options
author | Rafael Aquini <aquini@redhat.com> | 2023-09-08 19:06:49 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-10-06 14:57:03 +0200 |
commit | a5569bb187521432f509b69dda7d29f78b2d38b0 (patch) | |
tree | f49bf574e7851d60e5518cf98e8407f8d0839861 /mm | |
parent | 9a4fe81a8644b717d57d81ce5849e16583b13fe8 (diff) | |
download | linux-a5569bb187521432f509b69dda7d29f78b2d38b0.tar.gz |
mm/slab_common: fix slab_caches list corruption after kmem_cache_destroy()
commit 46a9ea6681907a3be6b6b0d43776dccc62cad6cf upstream.
After the commit in Fixes:, if a module that created a slab cache does not
release all of its allocated objects before destroying the cache (at rmmod
time), we might end up releasing the kmem_cache object without removing it
from the slab_caches list thus corrupting the list as kmem_cache_destroy()
ignores the return value from shutdown_cache(), which in turn never removes
the kmem_cache object from slabs_list in case __kmem_cache_shutdown() fails
to release all of the cache's slabs.
This is easily observable on a kernel built with CONFIG_DEBUG_LIST=y
as after that ill release the system will immediately trip on list_add,
or list_del, assertions similar to the one shown below as soon as another
kmem_cache gets created, or destroyed:
[ 1041.213632] list_del corruption. next->prev should be ffff89f596fb5768, but was 52f1e5016aeee75d. (next=ffff89f595a1b268)
[ 1041.219165] ------------[ cut here ]------------
[ 1041.221517] kernel BUG at lib/list_debug.c:62!
[ 1041.223452] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[ 1041.225408] CPU: 2 PID: 1852 Comm: rmmod Kdump: loaded Tainted: G B W OE 6.5.0 #15
[ 1041.228244] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20230524-3.fc37 05/24/2023
[ 1041.231212] RIP: 0010:__list_del_entry_valid+0xae/0xb0
Another quick way to trigger this issue, in a kernel with CONFIG_SLUB=y,
is to set slub_debug to poison the released objects and then just run
cat /proc/slabinfo after removing the module that leaks slab objects,
in which case the kernel will panic:
[ 50.954843] general protection fault, probably for non-canonical address 0xa56b6b6b6b6b6b8b: 0000 [#1] PREEMPT SMP PTI
[ 50.961545] CPU: 2 PID: 1495 Comm: cat Kdump: loaded Tainted: G B W OE 6.5.0 #15
[ 50.966808] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20230524-3.fc37 05/24/2023
[ 50.972663] RIP: 0010:get_slabinfo+0x42/0xf0
This patch fixes this issue by properly checking shutdown_cache()'s
return value before taking the kmem_cache_release() branch.
Fixes: 0495e337b703 ("mm/slab_common: Deleting kobject in kmem_cache_destroy() without holding slab_mutex/cpu_hotplug_lock")
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/slab_common.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 0042fb2730d1e1..4736c0e6093fa0 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -474,7 +474,7 @@ void slab_kmem_cache_release(struct kmem_cache *s) void kmem_cache_destroy(struct kmem_cache *s) { - int refcnt; + int err = -EBUSY; bool rcu_set; if (unlikely(!s) || !kasan_check_byte(s)) @@ -485,17 +485,17 @@ void kmem_cache_destroy(struct kmem_cache *s) rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; - refcnt = --s->refcount; - if (refcnt) + s->refcount--; + if (s->refcount) goto out_unlock; - WARN(shutdown_cache(s), - "%s %s: Slab cache still has objects when called from %pS", + err = shutdown_cache(s); + WARN(err, "%s %s: Slab cache still has objects when called from %pS", __func__, s->name, (void *)_RET_IP_); out_unlock: mutex_unlock(&slab_mutex); cpus_read_unlock(); - if (!refcnt && !rcu_set) + if (!err && !rcu_set) kmem_cache_release(s); } EXPORT_SYMBOL(kmem_cache_destroy); |