CVE-2023-52562 — mm/slab_common: fix slab_caches list corruption after kmem_cache_destroy()

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

mm/slab_common: fix slab_caches list corruption after kmem_cache_destroy()

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 kerne…

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CVE-2023-52562 — mm/slab_common: fix slab_caches list corruption after kmem_cache_destroy()