CVE-2026-90260

Status: UPDATED  |  Advisory ID: CVE-2026-90260

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

btrfs: zoned: don't clobber the extent buffer when zeroing it out

On a zoned filesystem a freed-but-still-dirty tree block is written out

as zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write

pointer advancing. btree_csum_one_bio() implemented this by memzeroing

the extent buffer's own folios before submission.

That destroys the in-memory buffer while it may still be referenced. In

particular btrfs_free_tree_block() can run on it afterwards and reads

the header to add a delayed reference; once the header has been zeroed

it frees bytenr 0 and corrupts the extent tree (the

btrfs_header_bytenr(buf) != 0 ASSERT in btrfs_free_tree_block(), or an

"unable to find ref" abort). It is flaky and reproduces under fsstress,

e.g. generic/461 and generic/013.

Write the zeros to disk from the shared zero page instead and leave the

extent buffer content untouched, so any later reference - including the

delayed reference from btrfs_free_tree_block() - still sees a valid

header. end_bbio_meta_write() now clears writeback on the buffer's own

folios, as the bio no longer carries them. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References