--- /dev/null
+From 637fd3cc21e4aacaf120b725f0aad9282f5f2126 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Tue, 4 Oct 2022 21:47:50 -0400
+Subject: net/ieee802154: don't warn zero-sized raw_sendmsg()
+
+From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
+
+[ Upstream commit b12e924a2f5b960373459c8f8a514f887adf5cac ]
+
+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.
+
+Link: https://syzkaller.appspot.com/bug?extid=5ea725c25d06fb9114c4 [1]
+Reported-by: syzbot <syzbot+5ea725c25d06fb9114c4@syzkaller.appspotmail.com>
+Fixes: fd1894224407c484 ("bpf: Don't redirect packets with invalid pkt_len")
+Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
+Signed-off-by: Alexander Aring <aahringo@redhat.com>
+Link: https://lore.kernel.org/r/20221005014750.3685555-2-aahringo@redhat.com
+Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ net/ieee802154/socket.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
+index c624a54502f3..aadd445ea88a 100644
+--- a/net/ieee802154/socket.c
++++ b/net/ieee802154/socket.c
+@@ -284,6 +284,10 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
+ err = -EMSGSIZE;
+ goto out_dev;
+ }
++ if (!size) {
++ err = 0;
++ goto out_dev;
++ }
+
+ hlen = LL_RESERVED_SPACE(dev);
+ tlen = dev->needed_tailroom;
+--
+2.35.1
+