diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-02-03 14:59:38 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-02-26 20:01:50 +0000 |
| commit | 5b746247d798a6061d213bf3f64c6e434bb4f23d (patch) | |
| tree | 5cdd8db7d90d901c1b0f3ac4d20f29b839a1c0e3 | |
| parent | c21341fd2c2e0e840864062707825d6d0d5e13b2 (diff) | |
tcp: avoid infinite loop in tcp_splice_read()
commit ccf7abb93af09ad0868ae9033d1ca8108bdaec82 upstream.
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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | net/ipv4/tcp.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 9ee5a4bbb289..068ffa698318 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -765,6 +765,12 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos, ret = -EAGAIN; break; } + /* 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); if (signal_pending(current)) { ret = sock_intr_errno(timeo); |