CVE-2026-98231

Summary

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

xfrm: serialize state GC with device state flush

The deferred-device pass in xfrm_dev_state_flush() finds states under xfrm_state_dev_gc_lock, but drops the lock before calling xfrm_dev_state_free() because the driver callback may sleep. The device GC list does not hold an xfrm_state reference, so the state GC worker can destroy the same state concurrently.

The race can proceed as follows:

CPU 0 CPU 1 find x on the device GC list drop xfrm_state_dev_gc_lock read x->xso.dev xfrm_state_gc_destroy(x) xfrm_dev_state_free(x) xfrm_state_free(x) continue xfrm_dev_state_free(x)

Both paths can invoke the driver callback and drop the device reference. CPU 0 can also access the xfrm_state after CPU 1 has freed it.

KASAN reported:

BUG: KASAN: slab-use-after-free in xfrm_dev_state_free+0x24c/0x2a0 Read of size 8 at addr ffff88810bbaa960 by task poc/102

Call Trace: xfrm_dev_state_free+0x24c/0x2a0 xfrm_dev_state_flush+0x353/0x400 xfrm_dev_event+0x26d/0x3a0 notifier_call_chain+0xc0/0x280 __dev_notify_flags+0x169/0x250 netif_change_flags+0xe7/0x160 dev_change_flags+0x96/0x220 devinet_ioctl+0x7f4/0x1880

Allocated by task 87: xfrm_state_alloc+0x1e/0x5c0 xfrm_add_sa+0xe7f/0x5820 xfrm_user_rcv_msg+0x4f3/0x940

Freed by task 57: kmem_cache_free+0xcb/0x3d0 xfrm_state_gc_task+0x4a8/0x650 process_one_work+0x63a/0x1070

Serialize xfrm_state destruction against the deferred-device pass with a mutex. Keep xfrm_state_dev_gc_lock limited to list operations and retain the existing callback and device-reference release ordering.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/937108dc0258d6ac69926b00bc53598c98986ee1
• https://git.kernel.org/stable/c/39e41af3653ee45c985190dd97426f318918d201
• https://git.kernel.org/stable/c/75fc4561772e2f9811abf39ed10443e6f4a4bc6c
• https://git.kernel.org/stable/c/84e378395494963b1e581cf223a7cbeec8c0e2d6
• https://git.kernel.org/stable/c/89fefad9f971bc637fb22373078144f2563c4be9

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