CVE-2023-53149 ext4: avoid deadlock in fs reclaim with page writeback
A deadlock in the Linux kernel ext4 filesystem can cause a denial of service during page writeback operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-53149?
CVE-2023-53149 is a medium-severity denial of service vulnerability in Linux kernel, published on 15 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ext4: avoid deadlock in fs reclaim with page writeback
Ext4 has a filesystem wide lock protecting ext4_writepages() calls to avoid races with switching of journalled data flag or inode format. This lock can however cause a deadlock like:
CPU0 CPU1
ext4_writepages() percpu_down_read(sbi->s_writepages_rwsem); ext4_change_inode_journal_flag() percpu_down_write(sbi->s_writepages_rwsem); - blocks, all readers block from now on ext4_do_writepages() ext4_init_io_end() kmem_cache_zalloc(io_end_cachep, GFP_KERNEL) fs_reclaim frees dentry... dentry_unlink_inode() iput() - last ref => iput_final() - inode dirty => write_inode_now()... ext4_writepages() tries to acquire sbi->s_writepages_rwsem and blocks forever
Make sure we cannot recurse into filesystem reclaim from writeback code to avoid the deadlock.
Weakness: CWE-667
Which versions are affected by CVE-2023-53149?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53149?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-53149 being exploited?
There is no known exploitation of CVE-2023-53149 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-70771, BELL-CVE-2023-53149, DEBIAN-CVE-2023-53149, GHSA-3gfc-6fjv-pj6m, ROOT-OS-DEBIAN-11-CVE-2023-53149, ROOT-OS-DEBIAN-12-CVE-2023-53149 and 2 more.