CVE-2026-68442 - btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

CVE-2026-68442 - btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

https://cvefeed.io/rssfeed/latest.atom / Wed, 08/12/2026 - 04:25
CVE ID :CVE-2026-68442
Published : Aug. 12, 2026, 12:17 a.m. | 1 hour, 10 minutes ago
Description :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.
Severity: 0.0 | NA
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