CVE-2026-74666

/// Technical description

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

packet: synchronize pressure clearing with ring reconfiguration

packet_set_ring() updates the RX ring state under sk_receive_queue.lock,

but used to publish the tpacket receive mode through po->prot_hook.func

after releasing that lock. packet_poll() and packet_recvmsg() can then

run the pressure clearing path after the ring has been cleared while

still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference

stale or NULL ring storage.

Move the existing receive hook assignment into the same

sk_receive_queue.lock section as the ring state update. Keep the

assignment otherwise unchanged, including on TX ring reconfiguration, to

avoid adding behavior changes that are not required for the fix.

Serialize packet_recvmsg() pressure clearing with the same queue lock

only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear

and the socket has moved away from tpacket_rcv, packet_set_ring() has

already

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References