CVE-2026-68442

Beschreibung

In the Linux kernel, the following vulnerability has been resolved: btrfs: don-t propagate EXTENT_FLAG_LOGGING to split extent maps When btrfs_drop_extent_map_range() splits an extent map, the new split maps inherit the original map-s flags through a local -flags- variable. Commit f86f7a75e2fb (-btrfs: use the flags of an extent map to identify the compression type-) changed the EXTENT_FLAG_LOGGING clearing to operate on em->flags instead of that local -flags- copy, so a split of an extent map that is currently being logged wrongly inherits EXTENT_FLAG_LOGGING. The flag is then never cleared on the split, and when it is freed while still on the inode-s modified_extents list (for example by the extent map shrinker) it trips the WARN_ON(!list_empty(&em->list)) in btrfs_free_extent_map() and leads to a use-after-free. Clear EXTENT_FLAG_LOGGING from the local -flags- copy used for the splits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the behaviour prior to f86f7a75e2fb.