UBUNTU-CVE-2025-21694
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.
02 / AFFECTED SOFTWARE
Affected packages
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/cbc5dde0a461240046e8a41c43d7c3b76d5db952
- https://git.kernel.org/stable/c/649b266606bc413407ce315f710c8ce8a88ee30a
- https://git.kernel.org/stable/c/65c367bd9d4f43513c7f837df5753bea9561b836
- https://git.kernel.org/stable/c/80828540dad0757b6337c6561d49c81038f38d87
- https://git.kernel.org/stable/c/80da29deb88a3a907441fc35bb7bac309f31e713
- https://git.kernel.org/stable/c/84c4ed15626574c9ac6c1039ba9c137a77bcc7f2
- https://git.kernel.org/stable/c/a5a2ee8144c3897d37403a69118c3e3dc5713958
- https://git.kernel.org/stable/c/cbc5dde0a461240046e8a41c43d7c3b76d5db952
- https://ubuntu.com/security/CVE-2025-21694
- https://ubuntu.com/security/notices/USN-7387-1
- https://ubuntu.com/security/notices/USN-7387-2
- https://ubuntu.com/security/notices/USN-7387-3
- https://ubuntu.com/security/notices/USN-7388-1
- https://ubuntu.com/security/notices/USN-7389-1
- https://ubuntu.com/security/notices/USN-7390-1
- https://ubuntu.com/security/notices/USN-7391-1
- https://ubuntu.com/security/notices/USN-7392-1
- https://ubuntu.com/security/notices/USN-7392-2
- https://ubuntu.com/security/notices/USN-7392-3
- https://ubuntu.com/security/notices/USN-7392-4
- https://ubuntu.com/security/notices/USN-7393-1
- https://ubuntu.com/security/notices/USN-7401-1
- https://ubuntu.com/security/notices/USN-7407-1
- https://ubuntu.com/security/notices/USN-7413-1
- https://ubuntu.com/security/notices/USN-7421-1
- https://ubuntu.com/security/notices/USN-7445-1
- https://ubuntu.com/security/notices/USN-7448-1
- https://ubuntu.com/security/notices/USN-7458-1
- https://ubuntu.com/security/notices/USN-7459-1
- https://ubuntu.com/security/notices/USN-7459-2
- https://ubuntu.com/security/notices/USN-7463-1
- https://ubuntu.com/security/notices/USN-7539-1
- https://ubuntu.com/security/notices/USN-7540-1
- https://ubuntu.com/security/notices/USN-7595-1
- https://ubuntu.com/security/notices/USN-7595-2
- https://ubuntu.com/security/notices/USN-7595-3
- https://ubuntu.com/security/notices/USN-7595-4
- https://ubuntu.com/security/notices/USN-7595-5
- https://ubuntu.com/security/notices/USN-7596-1
- https://ubuntu.com/security/notices/USN-7596-2
- https://ubuntu.com/security/notices/USN-7653-1
- https://www.cve.org/CVERecord?id=CVE-2025-21694