From 00c74b587197b0c503a8b1057a464ad13462444f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 2 Mar 2022 08:17:22 -0800 Subject: [PATCH] bpf, sockmap: Do not ignore orig_len parameter commit 60ce37b03917e593d8e5d8bcc7ec820773daf81d upstream. 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 Signed-off-by: Eric Dumazet Acked-by: John Fastabend Acked-by: Jakub Sitnicki Tested-by: Jakub Sitnicki Acked-by: Daniel Borkmann Link: https://lore.kernel.org/r/20220302161723.3910001-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/core/skmsg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 8eb671c..929a2b0 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1153,7 +1153,7 @@ static int sk_psock_verdict_recv(read_descriptor_t *desc, struct sk_buff *skb, 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); -- 2.7.4