CVE-2024-36966 erofs: reliably distinguish block based and fscache mode
A logic error in the Linux kernel EROFS filesystem can cause a kernel warning and potential denial of service when mounting in block device mode with on-demand features enabled.
- 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-2024-36966?
CVE-2024-36966 is a medium-severity vulnerability in Linux kernel, published on 8 Jun 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:
erofs: reliably distinguish block based and fscache mode
When erofs_kill_sb() is called in block dev based mode, s_bdev may not have been initialised yet, and if CONFIG_EROFS_FS_ONDEMAND is enabled, it will be mistaken for fscache mode, and then attempt to free an anon_dev that has never been allocated, triggering the following warning:
============================================ ida_free called for id=0 which is not allocated. WARNING: CPU: 14 PID: 926 at lib/idr.c:525 ida_free+0x134/0x140 Modules linked in: CPU: 14 PID: 926 Comm: mount Not tainted 6.9.0-rc3-dirty #630 RIP: 0010:ida_free+0x134/0x140 Call Trace: <TASK> erofs_kill_sb+0x81/0x90 deactivate_locked_super+0x35/0x80 get_tree_bdev+0x136/0x1e0 vfs_get_tree+0x2c/0xf0 do_new_mount+0x190/0x2f0 [...] ============================================
Now when erofs_kill_sb() is called, erofs_sb_info must have been initialised, so use sbi->fsid to distinguish between the two modes.
Weakness: CWE-824
Which versions are affected by CVE-2024-36966?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-36966?
Apply the vendor's patch.
Is CVE-2024-36966 being exploited?
There is no known exploitation of CVE-2024-36966 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-36966, DEBIAN-CVE-2024-36966, GHSA-9644-wv3x-7gcf, ROOT-OS-UBUNTU-2204-CVE-2024-36966, UBUNTU-CVE-2024-36966.