CVE-2025-39736

Summary

In the Linux kernel, the following vulnerability has been resolved:

mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock

When netpoll is enabled, calling pr_warn_once() while holding kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock inversion with the netconsole subsystem. This occurs because pr_warn_once() may trigger netpoll, which eventually leads to __alloc_skb() and back into kmemleak code, attempting to reacquire kmemleak_lock.

This is the path for the deadlock.

mem_pool_alloc() -> raw_spin_lock_irqsave(&kmemleak_lock, flags); -> pr_warn_once() -> netconsole subsystem -> netpoll -> __alloc_skb -> __create_object -> raw_spin_lock_irqsave(&kmemleak_lock, flags);

Fix this by setting a flag and issuing the pr_warn_once() after kmemleak_lock is released.

Affected Software

Weaknesses

ADP Enrichment

CVE Program Container

Additional References

• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

Additional References

• https://cert-portal.siemens.com/productcert/html/ssa-032379.html

References

• https://git.kernel.org/stable/c/c7b6ea0ede687e7460e593c5ea478f50aa41682a
• https://git.kernel.org/stable/c/4b0151e1d468eb2667c37b7af99b3c075072d334
• https://git.kernel.org/stable/c/f249d32bb54876b4b6c3ae071af8ddca77af390b
• https://git.kernel.org/stable/c/62879faa8efe8d8a9c7bf7606ee9c068012d7dac
• https://git.kernel.org/stable/c/1da95d3d4b7b1d380ebd87b71a61e7e6aed3265d
• https://git.kernel.org/stable/c/a0854de00ce2ee27edf39037e7836ad580eb3350
• https://git.kernel.org/stable/c/08f70be5e406ce47c822f2dd11c1170ca259605b
• https://git.kernel.org/stable/c/a181b228b37a6a5625dad2bb4265bb7abb673e9f
• https://git.kernel.org/stable/c/47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2

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