CVE-2022-50706: net/ieee802154: don't warn zero-sized raw_sendmsg()

In the Linux kernel, the following vulnerability has been resolved: net/ieee802154: don't warn zero-sized raw_sendmsg() syzbot is hitting skb_assert_len() warning at __dev_queue_xmit() [1], for PF_IEEE802154 socket's zero-sized raw_sendmsg() request is hitting __dev_queue_xmit() with skb->len == 0. Since PF_IEEE802154 socket's zero-sized raw_sendmsg() request was able to return 0, don't call __dev_queue_xmit() if packet length is 0. ---------- #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct sockaddr_in addr = { .sin_family = AF_INET, .sin_addr.s_addr = htonl(INADDR_LOOPBACK) }; struct iovec iov = { }; struct msghdr hdr = { .msg_name = &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1 }; sendmsg(socket(PF_IEEE802154, SOCK_RAW, 0), &hdr, 0); return 0; } ---------- Note that this might be a sign that commit fd1894224407c484 ("bpf: Don't redirect packets with invalid pkt_len") should be reverted, for skb->len == 0 was acceptable for at least PF_IEEE802154 socket.