CVE-2024-56586 f2fs: fix f2fs_bug_on when uninstalling filesystem call f2fs_evict_inode.
A local attacker can trigger a kernel bug check and crash the system by manipulating f2fs filesystem states during unmounting.
- 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-2024-56586?
CVE-2024-56586 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Dec 2024. 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:
f2fs: fix f2fs_bug_on when uninstalling filesystem call f2fs_evict_inode.
creating a large files during checkpoint disable until it runs out of space and then delete it, then remount to enable checkpoint again, and then unmount the filesystem triggers the f2fs_bug_on as below:
------------[ cut here ]------------ kernel BUG at fs/f2fs/inode.c:896! CPU: 2 UID: 0 PID: 1286 Comm: umount Not tainted 6.11.0-rc7-dirty #360 Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:f2fs_evict_inode+0x58c/0x610 Call Trace: __die_body+0x15/0x60 die+0x33/0x50 do_trap+0x10a/0x120 f2fs_evict_inode+0x58c/0x610 do_error_trap+0x60/0x80 f2fs_evict_inode+0x58c/0x610 exc_invalid_op+0x53/0x60 f2fs_evict_inode+0x58c/0x610 asm_exc_invalid_op+0x16/0x20 f2fs_evict_inode+0x58c/0x610 evict+0x101/0x260 dispose_list+0x30/0x50 evict_inodes+0x140/0x190 generic_shutdown_super+0x2f/0x150 kill_block_super+0x11/0x40 kill_f2fs_super+0x7d/0x140 deactivate_locked_super+0x2a/0x70 cleanup_mnt+0xb3/0x140 task_work_run+0x61/0x90
The root cause is: creating large files during disable checkpoint period results in not enough free segments, so when writing back root inode will failed in f2fs_enable_checkpoint. When umount the file system after enabling checkpoint, the root inode is dirty in f2fs_evict_inode function, which triggers BUG_ON. The steps to reproduce are as follows:
dd if=/dev/zero of=f2fs.img bs=1M count=55 mount f2fs.img f2fs_dir -o checkpoint=disable:10% dd if=/dev/zero of=big bs=1M count=50 sync rm big mount -o remount,checkpoint=enable f2fs_dir umount f2fs_dir
Let's redirty inode when there is not free segments during checkpoint is disable.
Which versions are affected by CVE-2024-56586?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-56586?
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-2024-56586 being exploited?
There is no known exploitation of CVE-2024-56586 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-56586, DEBIAN-CVE-2024-56586, GHSA-qm9m-jrmj-23f4, UBUNTU-CVE-2024-56586.