CVE-2026-64580

Summary

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

xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst()

On the error path where in6_dev_get(dev) returns NULL, xfrm6_fill_dst() releases the device reference with netdev_put() but leaves xdst->u.dst.dev set. dst_destroy() later calls netdev_put(dst->dev) again, so the same net_device reference is released twice, underflowing its refcount (ref_tracker WARNING + "unregister_netdevice: waiting for <dev> to become free").

Clear xdst->u.dst.dev after the netdev_put(), the same way the XFRM device-offload paths xfrm_dev_state_add() and xfrm_dev_policy_add() in net/xfrm/xfrm_device.c NULL ->dev when releasing the reference on error.

ref_tracker: reference already released. ref_tracker: allocated in: xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:86) … udpv6_sendmsg (net/ipv6/udp.c:1696) … ref_tracker: freed in: xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:90) … WARNING: lib/ref_tracker.c:322 at ref_tracker_free+0x58b/0x780 dst_destroy (net/core/dst.c:115) rcu_core handle_softirqs …

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/df6856c2dda9187601d29b5fbd7a81b3b178cedf
• https://git.kernel.org/stable/c/43de8a49335e611adb271bbd52e84dfbc11fc185
• https://git.kernel.org/stable/c/ff636d7b7cba6dea82ecf580415ea57f2c1a11b6
• https://git.kernel.org/stable/c/e078da1b4e11390cff3201c19a9a1fe70c5b934f
• https://git.kernel.org/stable/c/136992de9bb91871084ae52d172610541c76e4d2

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