CVE-2026-90261

CVE CVE-2026-90261EUVD EUVD-2026-81854Published 2026-09-17T16:07:58.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: flush active metadata block group at btree_writepages() start btree_writepages() writes the btree inode's dirty metadata in ascending logical address order. On a zoned filesystem only one metadata and one system block group is active for writing at a time, and check_bg_is_active() (via btrfs_check_meta_write_pointer()) pivots the active block group as writeback moves from one block group to the next. If the active block group sits at a higher logical address than another block group that also holds dirty metadata, the ascending walk reaches the lower one first and, to write it, has to finish the active block group and activate the lower one. It cannot finish a block group that still has unsent IO, and during WB_SYNC_ALL && !for_sync (commit) writeback it deliberately refuses to wait for that IO under fs_info->zoned_meta_io_lock, as that can deadlock. The pivot thus cannot issue the submission itself either, so it gives up: btrfs_check_meta_write_pointer() returns -EAGAIN, which btrfs_write_and_wait_transaction() treats as fatal and aborts the transaction, forcing the filesystem read-only. This happens intermittently under metadata-heavy relocation (e.g. fstests btrfs/187). Flush the active metadata and system block groups at the start of btree_writepages(), under the fs_info->zoned_meta_io_lock it already holds, so they have no unsent IO left and the later pivot can finish them and make forward progress.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75; 6.5.5 <6.6; 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 <e2de2989adb3e58c2320e57c255f52e065667b5e; 6.6; patch: 7.2.6; patch: 7.3-rc1; patch: 0; 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 <ecc05eda9a346848ae01a6c8bfa3f0bec133bd8b

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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