diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-02-03 14:59:38 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-02-06 22:38:55 -0500 |
| commit | ccf7abb93af09ad0868ae9033d1ca8108bdaec82 (patch) | |
| tree | a3d41e0f7a625bc45ea5396cfcf4a400284112cf /net | |
| parent | b3f2d07f4649adcf6905953a10d217b5683e4077 (diff) | |
| download | lwn-ccf7abb93af09ad0868ae9033d1ca8108bdaec82.tar.gz lwn-ccf7abb93af09ad0868ae9033d1ca8108bdaec82.zip | |
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>
Diffstat (limited to 'net')
| -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 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; 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, NULL); if (signal_pending(current)) { ret = sock_intr_errno(timeo); |