CVE-2026-74310

Status: UPDATED  |  Advisory ID: CVE-2026-74310

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

vhost/net: complete zerocopy ubufs only once

vhost-net initializes one ubuf_info per outstanding zerocopy TX

descriptor and hands it to the backend socket. The networking stack may

then clone a zerocopy skb before all skb references are released. For

example, batman-adv fragmentation reaches skb_split(), which calls

skb_zerocopy_clone() and increments the same ubuf_info refcount.

vhost_zerocopy_complete() currently treats every ubuf callback as a

completed vhost descriptor. It dereferences ubuf->ctx, writes the

descriptor completion state, and drops the vhost_net_ubuf_ref even when

the callback only releases a cloned skb reference. A backend reset can

therefore wait for and free the vhost_net_ubuf_ref while another cloned

skb still carries the same ubuf_info. A later completion then

dereferences the freed ubufs pointer.

KASAN reports the stale completion as:

BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x1d7/0x1f0

BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x101/0x1f0

vhost_zerocopy_complete

skb_copy_ubufs

__dev_forward_skb2

veth_xmit

The freed object was allocated from vhost_net_ioctl() while setting the

backend and freed through kfree_rcu()/kvfree_rcu_bulk after backend

removal, while delayed skb completion still reached

vhost_zerocopy_complete().

Honor the generic ubuf_info refcount before touching vhost state, and run

the vhost descriptor completion only for the final ubuf reference. This

matches the msg_zerocopy_complete() ownership rule for cloned zerocopy

skbs. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References