This is a note to let you know that I've just added the patch titled udp: Validate checksum in udp_read_sock() to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: udp-validate-checksum-in-udp_read_sock.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 631c42a4d99882ce396153f2343a77d6aa0738e0 Author: Cong Wang <cong.wang@xxxxxxxxxxxxx> Date: Sun Nov 14 20:40:06 2021 -0800 udp: Validate checksum in udp_read_sock() [ Upstream commit 099f896f498a2b26d84f4ddae039b2c542c18b48 ] It turns out the skb's in sock receive queue could have bad checksums, as both ->poll() and ->recvmsg() validate checksums. We have to do the same for ->read_sock() path too before they are redirected in sockmap. Fixes: d7f571188ecf ("udp: Implement ->read_sock() for sockmap") Reported-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: John Fastabend <john.fastabend@xxxxxxxxx> Link: https://lore.kernel.org/bpf/20211115044006.26068-1-xiyou.wangcong@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 2fffcf2b54f3f..2ce3fca545d37 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1808,6 +1808,17 @@ int udp_read_sock(struct sock *sk, read_descriptor_t *desc, skb = skb_recv_udp(sk, 0, 1, &err); if (!skb) return err; + + if (udp_lib_checksum_complete(skb)) { + __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, + IS_UDPLITE(sk)); + __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, + IS_UDPLITE(sk)); + atomic_inc(&sk->sk_drops); + kfree_skb(skb); + continue; + } + used = recv_actor(desc, skb, 0, skb->len); if (used <= 0) { if (!copied)