Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: fix deadlock between metadata writeback and transaction commit When writing out metadata extent buffers in a zoned filesystem, btree_writepages() holds fs_info->zoned_meta_io_lock across the whole writeback loop, including the call to btrfs_check_meta_write_pointer() -> check_bg_is_active(). For the tree-log block group, check_bg_is_active() may fail to activate the zone and fall back to btrfs_zone_finish_one_bg() to free an active zone. That path waits for the running transaction to commit while still holding zoned_meta_io_lock, but the committer needs that same lock to write out the tree extents, so the two tasks deadlock: Task A (kworker, metadata writeback) Task B (fsstress, transaction commit) ------------------------------------ ------------------------------------- wb_workfn() btrfs_commit_transaction(T) btree_writepages() btrfs_write_and_wait_transaction() btrfs_zoned_meta_io_lock() btrfs_write_marked_extents() btrfs_check_meta_write_pointer() btree_writepages() check_bg_is_active() [treelog_bg] btrfs_zoned_meta_io_lock() btrfs_zone_finish_one_bg() <blocks on zoned_meta_io_lock, btrfs_zone_finish() held by Task A> do_zone_finish() btrfs_inc_block_group_ro() btrfs_wait_for_commit() <blocks waiting for commit of transaction T, done by Task B> The sibling branch in check_bg_is_active() already drops zoned_meta_io_lock around do_zone_finish() for this exact reason. Do the same in the tree-log branch: release the lock around btrfs_zone_finish_one_bg() and re-acquire it afterwards. The lock only protects fs_info->active_{meta,system}_bg, which this branch does not touch, and ctx->zoned_bg keeps a reference to the block group across the unlock, so nothing is lost while the lock is dropped. This hang occasionally reproduces with fstests generic/475 on a zoned btrfs filesystem.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 before 18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd; affected 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 before c3320873e0c04ce7b746fc8fe948f07bbbbdec33; affected 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 before deddd28fd83c264ee2ff5cd6b34449a9f1be6112; affected 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 before 75859a7cd77cd2ddaddbcb963e3fcd34738953af; affected 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 before 1ebe51c29fa9755d5b2fea28727c051117907cf8; affected fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75; affected 6.5.5 before 6.6 |
| Linux / Linux | affected 6.6; unaffected 0 before 6.6; unaffected 6.6.151 through 6.6.*; unaffected 6.12.103 through 6.12.*; unaffected 6.18.44 through 6.18.*; unaffected 7.1.8 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd
- https://git.kernel.org/stable/c/c3320873e0c04ce7b746fc8fe948f07bbbbdec33
- https://git.kernel.org/stable/c/deddd28fd83c264ee2ff5cd6b34449a9f1be6112
- https://git.kernel.org/stable/c/75859a7cd77cd2ddaddbcb963e3fcd34738953af
- https://git.kernel.org/stable/c/1ebe51c29fa9755d5b2fea28727c051117907cf8
ADP enrichment
No English description supplied.
No references supplied.