From: Eric Dumazet <edumazet@google.com>

Date: Wed, 2 Mar 2022 08:17:22 -0800

Subject: bpf, sockmap: Do not ignore orig_len parameter

Patch-mainline: v5.17-rc7

Git-commit: 60ce37b03917e593d8e5d8bcc7ec820773daf81d

References: jsc#PED-1368

Currently, sk_psock_verdict_recv() returns skb->len

This is problematic because tcp_read_sock() might have

passed orig_len < skb->len, due to the presence of TCP urgent data.

This causes an infinite loop from tcp_read_sock()

Followup patch will make tcp_read_sock() more robust vs bad actors.

Fixes: ef5659280eb1 ("bpf, sockmap: Allow skipping sk_skb parser program")

Reported-by: syzbot <syzkaller@googlegroups.com>

Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: John Fastabend <john.fastabend@gmail.com>

Acked-by: Jakub Sitnicki <jakub@cloudflare.com>

Tested-by: Jakub Sitnicki <jakub@cloudflare.com>

Acked-by: Daniel Borkmann <daniel@iogearbox.net>

Link: https://lore.kernel.org/r/20220302161723.3910001-1-eric.dumazet@gmail.com

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>

---

 net/core/skmsg.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/core/skmsg.c

+++ b/net/core/skmsg.c

@@ -1153,7 +1153,7 @@ static int sk_psock_verdict_recv(read_de

 	struct sk_psock *psock;

 	struct bpf_prog *prog;

 	int ret = __SK_DROP;

-	int len = skb->len;

+	int len = orig_len;

 	/* clone here so sk_eat_skb() in tcp_read_sock does not drop our data */

 	skb = skb_clone(skb, GFP_ATOMIC);