From: Eric Dumazet edumazet@google.com
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 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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);