CVE-2026-80955 — dm-pcache: fix use-after-free and invalid seg operations in kset_replay()

Affected: Linux

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

dm-pcache: fix use-after-free and invalid seg operations in kset_replay()

In kset_replay, when key->seg_gen is stale (key->seg_gen < key->cache_pos.cache_seg->gen), cache_key_put(key) is called but then key->cache_pos.cache_seg is accessed as the argument to cache_seg_get(). This is a use-after-free on the freed key memory. Although mempool recycled memory is not immediately reclaimed or overwritten in practice, this is still a potential UAF bug.

Additionally, for expired invalid keys, setting the cache->seg_map bit and calling cache_seg_get() is unreasonable since the corresponding segment data is no longer valid.

Fix both issues by moving cache_seg_get() and __set_bit() after the gen check, so they only execute for valid keys, and using continue to skip invalid keys.

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CVE-2026-80955 — dm-pcache: fix use-after-free and invalid seg operations in kset_replay()