CVE-2026-23036
btrfs: release path before iget_failed() in btrfs_read_locked_inode()
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: release path before iget_failed() in btrfs_read_locked_inode() In btrfs_read_locked_inode() if we fail to lookup the inode, we jump to the 'out' label with a path that has a read locked leaf and then we call iget_failed(). This can result in a ABBA deadlock, since iget_failed() triggers inode eviction and that causes the release of the delayed inode, which must lock the delayed inode's mutex, and a task updating a delayed inode starts by taking the node's mutex and then modifying the inode's subvolume btree. Syzbot reported the following lockdep splat for this: ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ btrfs-cleaner/8725 is trying to acquire lock: ffff0000d6826a48 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290 but task is already holding lock: ffff0000dbeba878 (btrfs-tree-00){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x44/0x2ec fs/btrfs/locking.c:145 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (btrfs-tree-00){++++}-{4:4}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x198/0x39c kernel/locking/lockdep.c:5889 up_read+0x24/0x3c kernel/locking/rwsem.c:1632 btrfs_tree_read_unlock+0xdc/0x298 fs/btrfs/locking.c:169 btrfs_tree_unlock_rw fs/btrfs/locking.h:218 [inline] btrfs_search_slot+0xa6c/0x223c fs/btrfs/ctree.c:2133 btrfs_lookup_inode+0xd8/0x38c fs/btrfs/inode-item.c:395 __btrfs_update_delayed_inode+0x124/0xed0 fs/btrfs/delayed-inode.c:1032 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1118 [inline] __btrfs_commit_inode_delayed_items+0x15f8/0x1748 fs/btrfs/delayed-inode.c:1141 __btrfs_run_delayed_items+0x1ac/0x514 fs/btrfs/delayed-inode.c:1176 btrfs_run_delayed_items_nr+0x28/0x38 fs/btrfs/delayed-inode.c:1219 flush_space+0x26c/0xb68 fs/btrfs/space-info.c:828 do_async_reclaim_metadata_space+0x110/0x364 fs/btrfs/space-info.c:1158 btrfs_async_reclaim_metadata_space+0x90/0xd8 fs/btrfs/space-info.c:1226 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 -> #0 (&delayed_node->mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598 __mutex_lock kernel/locking/mutex.c:760 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812 __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290 btrfs_release_delayed_node fs/btrfs/delayed-inode.c:315 [inline] btrfs_remove_delayed_node+0x68/0x84 fs/btrfs/delayed-inode.c:1326 btrfs_evict_inode+0x578/0xe28 fs/btrfs/inode.c:5587 evict+0x414/0x928 fs/inode.c:810 iput_final fs/inode.c:1914 [inline] iput+0x95c/0xad4 fs/inode.c:1966 iget_failed+0xec/0x134 fs/bad_inode.c:248 btrfs_read_locked_inode+0xe1c/0x1234 fs/btrfs/inode.c:4101 btrfs_iget+0x1b0/0x264 fs/btrfs/inode.c:5837 btrfs_run_defrag_inode fs/btrfs/defrag.c:237 [inline] btrfs_run_defrag_inodes+0x520/0xdc4 fs/btrf ---truncated---
INFO
Published Date :
Jan. 31, 2026, 12:16 p.m.
Last Modified :
Jan. 31, 2026, 12:16 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-23036
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Apply the patch to btrfs_read_locked_inode().
- Ensure path is released before calling iget_failed().
- Test the fix in a Linux kernel environment.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-23036.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/1e1f2055ad5a7a5d548789b334a4473a7665c418 | |
| https://git.kernel.org/stable/c/65241e3ddda60b53a4ee3ae12721fc9ee21d5827 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-23036 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-23036
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-23036 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-23036 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jan. 31, 2026
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: btrfs: release path before iget_failed() in btrfs_read_locked_inode() In btrfs_read_locked_inode() if we fail to lookup the inode, we jump to the 'out' label with a path that has a read locked leaf and then we call iget_failed(). This can result in a ABBA deadlock, since iget_failed() triggers inode eviction and that causes the release of the delayed inode, which must lock the delayed inode's mutex, and a task updating a delayed inode starts by taking the node's mutex and then modifying the inode's subvolume btree. Syzbot reported the following lockdep splat for this: ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ btrfs-cleaner/8725 is trying to acquire lock: ffff0000d6826a48 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290 but task is already holding lock: ffff0000dbeba878 (btrfs-tree-00){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x44/0x2ec fs/btrfs/locking.c:145 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (btrfs-tree-00){++++}-{4:4}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x198/0x39c kernel/locking/lockdep.c:5889 up_read+0x24/0x3c kernel/locking/rwsem.c:1632 btrfs_tree_read_unlock+0xdc/0x298 fs/btrfs/locking.c:169 btrfs_tree_unlock_rw fs/btrfs/locking.h:218 [inline] btrfs_search_slot+0xa6c/0x223c fs/btrfs/ctree.c:2133 btrfs_lookup_inode+0xd8/0x38c fs/btrfs/inode-item.c:395 __btrfs_update_delayed_inode+0x124/0xed0 fs/btrfs/delayed-inode.c:1032 btrfs_update_delayed_inode fs/btrfs/delayed-inode.c:1118 [inline] __btrfs_commit_inode_delayed_items+0x15f8/0x1748 fs/btrfs/delayed-inode.c:1141 __btrfs_run_delayed_items+0x1ac/0x514 fs/btrfs/delayed-inode.c:1176 btrfs_run_delayed_items_nr+0x28/0x38 fs/btrfs/delayed-inode.c:1219 flush_space+0x26c/0xb68 fs/btrfs/space-info.c:828 do_async_reclaim_metadata_space+0x110/0x364 fs/btrfs/space-info.c:1158 btrfs_async_reclaim_metadata_space+0x90/0xd8 fs/btrfs/space-info.c:1226 process_one_work+0x7e8/0x155c kernel/workqueue.c:3263 process_scheduled_works kernel/workqueue.c:3346 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3427 kthread+0x5fc/0x75c kernel/kthread.c:463 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 -> #0 (&delayed_node->mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598 __mutex_lock kernel/locking/mutex.c:760 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812 __btrfs_release_delayed_node+0xa0/0x9b0 fs/btrfs/delayed-inode.c:290 btrfs_release_delayed_node fs/btrfs/delayed-inode.c:315 [inline] btrfs_remove_delayed_node+0x68/0x84 fs/btrfs/delayed-inode.c:1326 btrfs_evict_inode+0x578/0xe28 fs/btrfs/inode.c:5587 evict+0x414/0x928 fs/inode.c:810 iput_final fs/inode.c:1914 [inline] iput+0x95c/0xad4 fs/inode.c:1966 iget_failed+0xec/0x134 fs/bad_inode.c:248 btrfs_read_locked_inode+0xe1c/0x1234 fs/btrfs/inode.c:4101 btrfs_iget+0x1b0/0x264 fs/btrfs/inode.c:5837 btrfs_run_defrag_inode fs/btrfs/defrag.c:237 [inline] btrfs_run_defrag_inodes+0x520/0xdc4 fs/btrf ---truncated--- Added Reference https://git.kernel.org/stable/c/1e1f2055ad5a7a5d548789b334a4473a7665c418 Added Reference https://git.kernel.org/stable/c/65241e3ddda60b53a4ee3ae12721fc9ee21d5827