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 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.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel-headersUpgrade kernel-livepatch-6.1.56-82.125Upgrade perf-debuginfoUpgrade kernel-tools-develUpgrade perfUpgrade python3-perfUpgrade kernel-debuginfoUpgrade bpftoolUpgrade kernelUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-debuginfoUpgrade kernel-libbpf-develUpgrade kernel-libbpfUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-modules-extraUpgrade kernel-toolsUpgrade kernel-libbpf-staticUpgrade bpftool-debuginfoUpgrade python3-perf-debuginfoUpgrade kernel-devel | Feb 17, 2025 | Mar 2, 2024 |
| Debian | — | Upgrade linux | Jul 30, 2024 | Mar 2, 2024 |
| Redhat_linux | — | No solution existsUpgrade kernel | Jul 9, 2025 | Mar 2, 2024 |
| Ubuntu | — | Upgrade linux-awsUpgrade linux-raspiUpgrade linux-riscvUpgrade linux-oem-6.5Upgrade linux-oracle-6.5Upgrade linux-starfiveUpgrade linux-lowlatency-hwe-6.5Upgrade linux-lowlatencyUpgrade linux-gcp-6.5Upgrade linux-oracleUpgrade linux-laptopUpgrade linux-hwe-6.5Upgrade linuxUpgrade linux-gcpUpgrade linux-nvidia-6.5 | Nov 19, 2024 | Mar 2, 2024 |
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