CVE Published: 17/05/2024 |
CVE Updated: 12/11/2024 |
CVE Year: 2024 Source: Linux |
Vendor: Linux |
Product: Linux Status : PUBLISHED
CVE-2024-35797 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.