Description

In the Linux kernel, the following vulnerability has been resolved: mm: cachestat: fix two shmem bugs When cachestat on shmem races with swapping and invalidation, there are two possible bugs: 1) A swapin error can have resulted in a poisoned swap entry in the shmem inode's xarray. Calling get_shadow_from_swap_cache() on it will result in an out-of-bounds access to swapper_spaces[]. Validate the entry with non_swap_entry() before going further. 2) When we find a valid swap entry in the shmem's inode, the shadow entry in the swapcache might not exist yet: swap IO is still in progress and we're before __remove_mapping; swapin, invalidation, or swapoff have removed the shadow from swapcache after we saw the shmem swap entry. This will send a NULL to workingset_test_recent(). The latter purely operates on pointer bits, so it won't crash - node 0, memcg ID 0, eviction timestamp 0, etc. are all valid inputs - but it's a bogus test. In theory that could result in a false "recently evicted" count. Such a false positive wouldn't be the end of the world. But for code clarity and (future) robustness, be explicit about this case. Bail on get_shadow_from_swap_cache() returning NULL.

Metrics

 

CVSS Version 4.0 CVSS Version 3.x CVSS Version 2.0

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

CVSS 3.x Severity and Vector Strings:

NIST: NVD

Base Score:  N/A

NVD assessment not yet provided.

ADP:  CISA-ADP

Base Score:  5.3 MEDIUM

Vector:  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS 2.0 Severity and Vector Strings:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

CISA-ADP AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CISA-ADP CWE-787

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

mm: cachestat: fix two shmem bugs

When cachestat on shmem races with swapping and invalidation, there
are two possible bugs:

1) A swapin error can have resulted in a poisoned swap entry in the
   shmem inode's xarray. Calling get_shadow_from_swap_cache() on it
   will result in an out-of-bounds access to swapper_spaces[].

   Validate the entry with non_swap_entry() before going further.

2) When we find a valid swap entry in

kernel.org https://git.kernel.org/stable/c/24a0e73d544439bb9329fbbafac44299e548a677 [No types assigned]

kernel.org https://git.kernel.org/stable/c/b79f9e1ff27c994a4c452235ba09e672ec698e23 [No types assigned]

kernel.org https://git.kernel.org/stable/c/d5d39c707a4cf0bcc84680178677b97aa2cb2627 [No types assigned]

kernel.org https://git.kernel.org/stable/c/d962f6c583458037dc7e529659b2b02b9dd3d94b [No types assigned]