CVE-2024-36908 blk-iocost: do not WARN if iocg was already offlined
A logic error in the Linux kernel's blk-iocost module triggers unnecessary warnings during device removal, potentially causing system instability or denial of service.
- 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-2024-36908?
CVE-2024-36908 is a high-severity denial of service vulnerability in Linux kernel, published on 30 May 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:
blk-iocost: do not WARN if iocg was already offlined
In iocg_pay_debt(), warn is triggered if 'active_list' is empty, which is intended to confirm iocg is active when it has debt. However, warn can be triggered during a blkcg or disk removal, if iocg_waitq_timer_fn() is run at that time:
WARNING: CPU: 0 PID: 2344971 at block/blk-iocost.c:1402 iocg_pay_debt+0x14c/0x190 Call trace: iocg_pay_debt+0x14c/0x190 iocg_kick_waitq+0x438/0x4c0 iocg_waitq_timer_fn+0xd8/0x130 __run_hrtimer+0x144/0x45c __hrtimer_run_queues+0x16c/0x244 hrtimer_interrupt+0x2cc/0x7b0
The warn in this situation is meaningless. Since this iocg is being removed, the state of the 'active_list' is irrelevant, and 'waitq_timer' is canceled after removing 'active_list' in ioc_pd_free(), which ensures iocg is freed after iocg_waitq_timer_fn() returns.
Therefore, add the check if iocg was already offlined to avoid warn when removing a blkcg or disk.
Which versions are affected by CVE-2024-36908?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-36908?
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-2024-36908 being exploited?
There is no known exploitation of CVE-2024-36908 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-36908, DEBIAN-CVE-2024-36908, ROOT-OS-UBUNTU-2204-CVE-2024-36908, UBUNTU-CVE-2024-36908.