Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 045/126] tcp: initialize tp->copied_seq in case of cross SYN connection | Date | Wed, 6 Jan 2016 10:36:14 +0000 |
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3.16.7-ckt22 -stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
commit 142a2e7ece8d8ac0e818eb2c91f99ca894730e2a upstream.
Dmitry provided a syzkaller (http://github.com/google/syzkaller) generated program that triggers the WARNING at net/ipv4/tcp.c:1729 in tcp_recvmsg() :
WARN_ON(tp->copied_seq != tp->rcv_nxt && !(flags & (MSG_PEEK | MSG_TRUNC)));
His program is specifically attempting a Cross SYN TCP exchange, that we support (for the pleasure of hackers ?), but it looks we lack proper tcp->copied_seq initialization.
Thanks again Dmitry for your report and testings.
Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/ipv4/tcp_input.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e3d40a303b8f..43404d3f9da8 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5549,6 +5549,7 @@ discard: } tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; + tp->copied_seq = tp->rcv_nxt; tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1; /* RFC1323: The window in SYN & SYN/ACK segments is
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