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authorEric Dumazet <edumazet@google.com>2017-02-03 14:59:38 -0800
committerDavid S. Miller <davem@davemloft.net>2017-02-06 22:38:55 -0500
commitccf7abb93af09ad0868ae9033d1ca8108bdaec82 (patch)
parentb3f2d07f4649adcf6905953a10d217b5683e4077 (diff)
tcp: avoid infinite loop in tcp_splice_read()
Splicing from TCP socket is vulnerable when a packet with URG flag is received and stored into receive queue. __tcp_splice_read() returns 0, and sk_wait_data() immediately returns since there is the problematic skb in queue. This is a nice way to burn cpu (aka infinite loop) and trigger soft lockups. Again, this gem was found by syzkaller tool. Fixes: 9c55e01c0cc8 ("[TCP]: Splice receive support.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 6 insertions, 0 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4a044964da66..0efb4c7f6704 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -770,6 +770,12 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
ret = -EAGAIN;
+ /* if __tcp_splice_read() got nothing while we have
+ * an skb in receive queue, we do not want to loop.
+ * This might happen with URG data.
+ */
+ if (!skb_queue_empty(&sk->sk_receive_queue))
+ break;
sk_wait_data(sk, &timeo, NULL);
if (signal_pending(current)) {
ret = sock_intr_errno(timeo);