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[PULL,1/1] slirp: don't zero the whole ti_i when m == NULL

Message ID 20171109180142.13923-2-samuel.thibault@ens-lyon.org
State New
Headers show
Series [PULL,1/1] slirp: don't zero the whole ti_i when m == NULL | expand

Commit Message

Samuel Thibault Nov. 9, 2017, 6:01 p.m. UTC 
From: Tao Wu <lepton@google.com>

98c63057d2144fb81681580cd84c13c93794c96e ('slirp: Factorizing
tcpiphdr structure with an union') introduced a memset call to clear
possibly-undefined fields in ti. This however overwrites src/dst/pr which
are used below.

So let us clear only the unused fields.

This should fix some rare cases (some RST cases, keep alive probes)
where packets would be sent to 0.0.0.0.

Signed-off-by: Tao Wu <lepton@google.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
---
 slirp/tcp_subr.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
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Patch

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index dc8b4bbb50..da0d53743f 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -148,7 +148,16 @@  tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
 		m->m_data += IF_MAXLINKHDR;
 		*mtod(m, struct tcpiphdr *) = *ti;
 		ti = mtod(m, struct tcpiphdr *);
-		memset(&ti->ti, 0, sizeof(ti->ti));
+		switch (af) {
+		case AF_INET:
+		    ti->ti.ti_i4.ih_x1 = 0;
+		    break;
+		case AF_INET6:
+		    ti->ti.ti_i6.ih_x1 = 0;
+		    break;
+		default:
+		    g_assert_not_reached();
+		}
 		flags = TH_ACK;
 	} else {
 		/*