CVE-2026-74310

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> vhost/net: complete zerocopy ubufs only once<br /> <br /> vhost-net initializes one ubuf_info per outstanding zerocopy TX<br /> descriptor and hands it to the backend socket. The networking stack may<br /> then clone a zerocopy skb before all skb references are released. For<br /> example, batman-adv fragmentation reaches skb_split(), which calls<br /> skb_zerocopy_clone() and increments the same ubuf_info refcount.<br /> <br /> vhost_zerocopy_complete() currently treats every ubuf callback as a<br /> completed vhost descriptor. It dereferences ubuf-&gt;ctx, writes the<br /> descriptor completion state, and drops the vhost_net_ubuf_ref even when<br /> the callback only releases a cloned skb reference. A backend reset can<br /> therefore wait for and free the vhost_net_ubuf_ref while another cloned<br /> skb still carries the same ubuf_info. A later completion then<br /> dereferences the freed ubufs pointer.<br /> <br /> KASAN reports the stale completion as:<br /> <br /> BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x1d7/0x1f0<br /> BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x101/0x1f0<br /> vhost_zerocopy_complete<br /> skb_copy_ubufs<br /> __dev_forward_skb2<br /> veth_xmit<br /> <br /> The freed object was allocated from vhost_net_ioctl() while setting the<br /> backend and freed through kfree_rcu()/kvfree_rcu_bulk after backend<br /> removal, while delayed skb completion still reached<br /> vhost_zerocopy_complete().<br /> <br /> Honor the generic ubuf_info refcount before touching vhost state, and run<br /> the vhost descriptor completion only for the final ubuf reference. This<br /> matches the msg_zerocopy_complete() ownership rule for cloned zerocopy<br /> skbs.