CVE-2025-21694: fs/proc: fix softlockup in __read_vmcore (part 2)
First published: Wed Feb 12 2025(Updated: )
In the Linux kernel, the following vulnerability has been resolved: fs/proc: fix softlockup in __read_vmcore (part 2) Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes. In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck. The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough. Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux kernel | ||
| Linux kernel | >=4.19.317<4.20 | |
| Linux kernel | >=5.4.279<5.4.290 | |
| Linux kernel | >=5.10.221<5.10.234 | |
| Linux kernel | >=5.15.162<5.15.177 | |
| Linux kernel | >=6.1.95<6.1.127 | |
| Linux kernel | >=6.6.35<6.6.74 | |
| Linux kernel | >=6.9.6<6.12.11 | |
| Linux kernel | =6.13-rc1 | |
| Linux kernel | =6.13-rc2 | |
| Linux kernel | =6.13-rc3 | |
| Linux kernel | =6.13-rc4 | |
| Linux kernel | =6.13-rc5 | |
| Linux kernel | =6.13-rc6 | |
| Linux kernel | =6.13-rc7 |
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Reference Links
- https://git.kernel.org/stable/c/84c4ed15626574c9ac6c1039ba9c137a77bcc7f2
- https://git.kernel.org/stable/c/80da29deb88a3a907441fc35bb7bac309f31e713
- https://git.kernel.org/stable/c/649b266606bc413407ce315f710c8ce8a88ee30a
- https://git.kernel.org/stable/c/65c367bd9d4f43513c7f837df5753bea9561b836
- https://git.kernel.org/stable/c/a5a2ee8144c3897d37403a69118c3e3dc5713958
- https://git.kernel.org/stable/c/80828540dad0757b6337c6561d49c81038f38d87
- https://git.kernel.org/stable/c/cbc5dde0a461240046e8a41c43d7c3b76d5db952
Frequently Asked Questions
What is the severity of CVE-2025-21694?
CVE-2025-21694 has been classified with a moderate severity level due to the risk of soft lockups during kdump operations.
How do I fix CVE-2025-21694?
To address CVE-2025-21694, it is recommended to update the Linux kernel to the latest stable version where the vulnerability has been resolved.
What systems are affected by CVE-2025-21694?
CVE-2025-21694 affects the Linux kernel across various distributions that utilize the kernel's proc filesystem.
What are the potential impacts of CVE-2025-21694?
The potential impacts of CVE-2025-21694 include system instability and hangs during memory dump operations.
When was CVE-2025-21694 reported?
CVE-2025-21694 was reported and subsequently addressed after encountering issues in the Linux kernel related to softlockups during kdump.
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