Commit 0741be35 authored Aug 27, 2019 by Petar Penkov Committed by Daniel Borkmann Aug 31, 2019

bpf: fix error check in bpf_tcp_gen_syncookie



If a SYN cookie is not issued by tcp_v#_gen_syncookie, then the return
value will be exactly 0, rather than <= 0. Let's change the check to
reflect that, especially since mss is an unsigned value and cannot be
negative.

Fixes: 70d66244 ("bpf: add bpf_tcp_gen_syncookie helper")
Reported-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Petar Penkov <ppenkov@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

parent 736a5530

net/core/filter.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5903,7 +5903,7 @@ BPF_CALL_5(bpf_tcp_gen_syncookie, struct sock , sk, void , iph, u32, iph_len,
		default:
		return -EPROTONOSUPPORT;
		}
		if (mss <= 0)
		if (mss == 0)
		return -ENOENT;

		return cookie \| ((u64)mss << 32);

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