CVE-2024-40976 drm/lima: mask irqs in timeout path before hard reset
A race condition in the Linux kernel's Lima GPU driver can cause a refcount imbalance and system warning, potentially leading to 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-2024-40976?
CVE-2024-40976 is a medium-severity vulnerability in Linux kernel, published on 12 Jul 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:
drm/lima: mask irqs in timeout path before hard reset
There is a race condition in which a rendering job might take just long enough to trigger the drm sched job timeout handler but also still complete before the hard reset is done by the timeout handler. This runs into race conditions not expected by the timeout handler. In some very specific cases it currently may result in a refcount imbalance on lima_pm_idle, with a stack dump such as:
[10136.669170] WARNING: CPU: 0 PID: 0 at drivers/gpu/drm/lima/lima_devfreq.c:205 lima_devfreq_record_idle+0xa0/0xb0 ... [10136.669459] pc : lima_devfreq_record_idle+0xa0/0xb0 ... [10136.669628] Call trace: [10136.669634] lima_devfreq_record_idle+0xa0/0xb0 [10136.669646] lima_sched_pipe_task_done+0x5c/0xb0 [10136.669656] lima_gp_irq_handler+0xa8/0x120 [10136.669666] __handle_irq_event_percpu+0x48/0x160 [10136.669679] handle_irq_event+0x4c/0xc0
We can prevent that race condition entirely by masking the irqs at the beginning of the timeout handler, at which point we give up on waiting for that job entirely. The irqs will be enabled again at the next hard reset which is already done as a recovery by the timeout handler.
Weakness: CWE-362
Which versions are affected by CVE-2024-40976?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-40976?
Apply the vendor's patch.
Is CVE-2024-40976 being exploited?
There is no known exploitation of CVE-2024-40976 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-40976, DEBIAN-CVE-2024-40976, GHSA-8xmj-h9j2-77ww, UBUNTU-CVE-2024-40976.