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| author | Leo Martins <loemra.dev@gmail.com> | 2026-06-30 12:58:05 -0700 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2026-07-14 07:04:22 +0200 |
| commit | 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644 (patch) | |
| tree | 352a62d3f6df605eadceb2169b8b396e3754c292 /fs/btrfs | |
| parent | 8b5a09ceb61b18b1f0797cd30a549d7dc85d8d50 (diff) | |
| download | linux-next-5eff4d5b17fa1950e80bfd1ba43dc0699e61a644.tar.gz linux-next-5eff4d5b17fa1950e80bfd1ba43dc0699e61a644.zip | |
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.
CC: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/all/20260629-btrfs-skip-logging-v1-1-4e3a28c1acaf@kernel.org/
Fixes: f86f7a75e2fb ("btrfs: use the flags of an extent map to identify the compression type")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Leo Martins <loemra.dev@gmail.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/extent_map.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index fce9c5cc0122..6ad7b39ae358 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -866,13 +866,13 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end, goto next; } - flags = em->flags; /* * In case we split the extent map, we want to preserve the * EXTENT_FLAG_LOGGING flag on our extent map, but we don't want * it on the new extent maps. */ - em->flags &= ~(EXTENT_FLAG_PINNED | EXTENT_FLAG_LOGGING); + flags = em->flags & ~EXTENT_FLAG_LOGGING; + em->flags &= ~EXTENT_FLAG_PINNED; modified = !list_empty(&em->list); /* |