CVE-2020-36787 media: aspeed: fix clock handling logic
A kernel driver bug causes random memory corruption and kernel panics on specific Aspeed SoCs, requiring a patch to fix clock handling logic.
- 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-2020-36787?
CVE-2020-36787 is a high-severity memory corruption vulnerability in Linux kernel, published on 28 Feb 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:
media: aspeed: fix clock handling logic
Video engine uses eclk and vclk for its clock sources and its reset control is coupled with eclk so the current clock enabling sequence works like below.
Enable eclk De-assert Video Engine reset 10ms delay Enable vclk
It introduces improper reset on the Video Engine hardware and eventually the hardware generates unexpected DMA memory transfers that can corrupt memory region in random and sporadic patterns. This issue is observed very rarely on some specific AST2500 SoCs but it causes a critical kernel panic with making a various shape of signature so it's extremely hard to debug. Moreover, the issue is observed even when the video engine is not actively used because udevd turns on the video engine hardware for a short time to make a query in every boot.
To fix this issue, this commit changes the clock handling logic to make the reset de-assertion triggered after enabling both eclk and vclk. Also, it adds clk_unprepare call for a case when probe fails.
clk: ast2600: fix reset settings for eclk and vclk Video engine reset setting should be coupled with eclk to match it with the setting for previous Aspeed SoCs which is defined in clk-aspeed.c since all Aspeed SoCs are sharing a single video engine driver. Also, reset bit 6 is defined as 'Video Engine' reset in datasheet so it should be de-asserted when eclk is enabled. This commit fixes the setting.
Which versions are affected by CVE-2020-36787?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2020-36787?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2020-36787 being exploited?
There is no known exploitation of CVE-2020-36787 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2020-36787, GHSA-9hx5-6xv8-6w7c, UBUNTU-CVE-2020-36787.