CVE-2026-98850net/packet: prevent TX_RING byte count overflow

Official description

In the Linux kernel, the following vulnerability has been resolved: net/packet: prevent TX_RING byte count overflow tpacket_snd() drains every SEND_REQUEST frame in a TX ring and adds each valid packet length to the signed int len_sum. Userspace can recycle completed frames concurrently, so a single blocking send call is not bounded by the ring size. After enough successful transmissions len_sum wraps into the negative range. In particular, 65536 65535-byte frames followed by a 65007-byte frame produce 0xfffffdef, or -EIOCBQUEUED. sock_sendmsg_nosec() treats that as an impossible return and triggers a BUG. On systems configured to panic on oops, a CAP_NET_RAW holder can panic the host kernel. Stop before the next frame would make the byte count exceed INT_MAX. The positive short count leaves that frame pending for a later send call. A two-thread TPACKET_V2 reproducer triggered the BUG on an arm64 build of Linux 7.3-rc4. With this change, the same reproducer returned the expected positive short count without an oops.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/1e6ee93cea4b77253b1b81eb5759899f959ebee3
• https://git.kernel.org/stable/c/70fefff0801d4c5405e515592d1e7ad1351530cd
• https://git.kernel.org/stable/c/4848c175b5984e6358bcca794ac1dee4d527efcc
• https://git.kernel.org/stable/c/ae169d318d5d23bac76ece90a7e2b5cb760ed043
• https://git.kernel.org/stable/c/be12b221c0301111eeb023be04add3c6ad7c21fe
• https://git.kernel.org/stable/c/69ca64bbb528898916f309552053c32a04a36ebc
• https://git.kernel.org/stable/c/9fd63d284e251332f4874ef9023cde472f315f86
• https://git.kernel.org/stable/c/2cf81fc9505b148b1b70068303ea6ea4b1212403