cbcvebase.
CVE-2022-49700
published 2025-02-26

CVE-2022-49700: In the Linux kernel, the following vulnerability has been resolved: mm/slub: add missing TID updates on slab deactivation The fastpath in slab_alloc_node()…

PriorityP340high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.28%
20.3th percentile
In the Linux kernel, the following vulnerability has been resolved: mm/slub: add missing TID updates on slab deactivation The fastpath in slab_alloc_node() assumes that c->slab is stable as long as the TID stays the same. However, two places in __slab_alloc() currently don't update the TID when deactivating the CPU slab. If multiple operations race the right way, this could lead to an object getting lost; or, in an even more unlikely situation, it could even lead to an object being freed onto the wrong slab's freelist, messing up the `inuse` counter and eventually causing a page to be freed to the page allocator while it still contains slab objects. (I haven't actually tested these cases though, this is just based on looking at the code. Writing testcases for this stuff seems like it'd be a pain...) The race leading to state inconsistency is (all operations on the same CPU and kmem_cache): - task A: begin do_slab_free(): - read TID - read pcpu freelist (==NULL) - check `slab == c->slab` (true) - [PREEMPT A->B] - task B: begin slab_alloc_node(): - fastpath fails (`c->freelist` is NULL) - enter __slab_alloc() - slub_get_cpu_ptr() (disables preemption) - enter ___slab_alloc() - take local_lock_irqsave() - read c->freelist as NULL - get_freelist() returns NULL - write `c->slab = NULL` - drop local_unlock_irqrestore() - goto new_slab - slub_percpu_partial() is NULL - get_partial() returns NULL - slub_put_cpu_ptr() (enables preemption) - [PREEMPT B->A] - task A: finish do_slab_free(): - this_cpu_cmpxchg_double() succeeds() - [CORRUPT STATE: c->slab==NULL, c->freelist!=NULL] From there, the object on c->freelist will get lost if task B is allowed to continue from here: It will proceed to the retry_load_slab label, set c->slab, then jump to load_freelist, which clobbers c->freelist. But if we instead continue as follows, we get worse corruption: - task A: run __slab_free() on object from other struct slab: - CPU_PARTIAL_FREE case (slab was on no list, is now on pcp

Affected

22 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.18.14-1 (bookworm)linux 5.18.14-1 (bookworm)
linuxlinux——
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < 308c6d0e1f200fd26c71270c6e6bfcf0fc6ff082308c6d0e1f200fd26c71270c6e6bfcf0fc6ff082
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < d6a597450e686d4c6388bd3cdcb17224b4dae7f0d6a597450e686d4c6388bd3cdcb17224b4dae7f0
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < e2b2f0e2e34d71ae6c2a1114fd3c525930e84bc7e2b2f0e2e34d71ae6c2a1114fd3c525930e84bc7
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < e7e3e90d671078455a3a08189f89d85b3da2de9ee7e3e90d671078455a3a08189f89d85b3da2de9e
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < 6c32496964da0dc230cea763a0e934b2e02dabd56c32496964da0dc230cea763a0e934b2e02dabd5
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < 0515cc9b6b24877f59b222ade704bfaa42caa2a60515cc9b6b24877f59b222ade704bfaa42caa2a6
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < 197e257da473c725dfe47759c3ee02f2398d8ea5197e257da473c725dfe47759c3ee02f2398d8ea5
linuxlinux>= 03e404af26dc2ea0d278d7a342de0aab394793ce < eeaa345e128515135ccb864c04482180c08e3259eeaa345e128515135ccb864c04482180c08e3259
linuxlinux_kernel——
linuxlinux_kernel>= 0 < 5.10.136-15.10.136-1
linuxlinux_kernel>= 0 < 5.18.14-15.18.14-1
linuxlinux_kernel>= 0 < 5.18.14-15.18.14-1
linuxlinux_kernel>= 0 < 5.18.14-15.18.14-1
linuxlinux_kernel>= 3.1 < 4.9.3234.9.323
linuxlinux_kernel>= 4.10 < 4.14.2884.14.288
linuxlinux_kernel>= 4.15 < 4.19.2524.19.252
linuxlinux_kernel>= 4.20 < 5.4.2055.4.205
linuxlinux_kernel>= 5.11 < 5.15.545.15.54
linuxlinux_kernel>= 5.16 < 5.18.85.18.8
linuxlinux_kernel>= 5.5 < 5.10.1305.10.130

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv7.8HIGH
vendor_debian7.8HIGH
vendor_redhat7.8HIGH
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