CVE-2025-39736
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.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 5.4 | 5.4.297 |
| linux / linux_kernel | 5.5 | 5.10.241 |
| linux / linux_kernel | 5.11 | 5.15.190 |
| linux / linux_kernel | 5.16 | 6.1.149 |
| linux / linux_kernel | 6.2 | 6.6.103 |
| linux / linux_kernel | 6.7 | 6.12.43 |
| linux / linux_kernel | 6.13 | 6.15.11 |
| linux / linux_kernel | 6.16 | 6.16.2 |
| linux / linux_kernel | 6.17-rc1 | 6.17-rc1.x |
| debian / debian_linux | 11.0 | 11.0.x |
- https://git.kernel.org/stable/c/08f70be5e406ce47c822f2dd11c1170ca259605b
- https://git.kernel.org/stable/c/1da95d3d4b7b1d380ebd87b71a61e7e6aed3265d
- https://git.kernel.org/stable/c/47b0f6d8f0d2be4d311a49e13d2fd5f152f492b2
- https://git.kernel.org/stable/c/4b0151e1d468eb2667c37b7af99b3c075072d334
- https://git.kernel.org/stable/c/62879faa8efe8d8a9c7bf7606ee9c068012d7dac
- https://git.kernel.org/stable/c/a0854de00ce2ee27edf39037e7836ad580eb3350
- https://git.kernel.org/stable/c/a181b228b37a6a5625dad2bb4265bb7abb673e9f
- https://git.kernel.org/stable/c/c7b6ea0ede687e7460e593c5ea478f50aa41682a
- https://git.kernel.org/stable/c/f249d32bb54876b4b6c3ae071af8ddca77af390b
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
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