CVE-2023-52738 drm/amdgpu/fence: Fix oops due to non-matching drm_sched init/fini
A null pointer dereference in the amdgpu driver causes a kernel oops and system crash when device initialization fails.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-52738?
CVE-2023-52738 is a medium-severity vulnerability in Linux kernel, published on 21 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/fence: Fix oops due to non-matching drm_sched init/fini
Currently amdgpu calls drm_sched_fini() from the fence driver sw fini routine - such function is expected to be called only after the respective init function - drm_sched_init() - was executed successfully.
Happens that we faced a driver probe failure in the Steam Deck recently, and the function drm_sched_fini() was called even without its counter-part had been previously called, causing the following oops:
amdgpu: probe of 0000:04:00.0 failed with error -110 BUG: kernel NULL pointer dereference, address: 0000000000000090 PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP NOPTI CPU: 0 PID: 609 Comm: systemd-udevd Not tainted 6.2.0-rc3-gpiccoli #338 Hardware name: Valve Jupiter/Jupiter, BIOS F7A0113 11/04/2022 RIP: 0010:drm_sched_fini+0x84/0xa0 [gpu_sched] [...] Call Trace: <TASK> amdgpu_fence_driver_sw_fini+0xc8/0xd0 [amdgpu] amdgpu_device_fini_sw+0x2b/0x3b0 [amdgpu] amdgpu_driver_release_kms+0x16/0x30 [amdgpu] devm_drm_dev_init_release+0x49/0x70 [...]
To prevent that, check if the drm_sched was properly initialized for a given ring before calling its fini counter-part.
Notice ideally we'd use sched.ready for that; such field is set as the latest thing on drm_sched_init(). But amdgpu seems to "override" the meaning of such field - in the above oops for example, it was a GFX ring causing the crash, and the sched.ready field was set to true in the ring init routine, regardless of the state of the DRM scheduler. Hence, we ended-up using sched.ops as per Christian's suggestion [0], and also removed the no_scheduler check [1].
[0] https://lore.kernel.org/amd-gfx/[email protected]/ [1] https://lore.kernel.org/amd-gfx/[email protected]/
Weakness: CWE-476
Which versions are affected by CVE-2023-52738?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-52738?
Apply the vendor's patch.
Is CVE-2023-52738 being exploited?
There is no known exploitation of CVE-2023-52738 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-52738, DEBIAN-CVE-2023-52738, GHSA-95mq-4jg4-hpq2, UBUNTU-CVE-2023-52738.