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43 lines
1.4 KiB
Diff
43 lines
1.4 KiB
Diff
From ccf7abb93af09ad0868ae9033d1ca8108bdaec82 Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <edumazet@google.com>
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Date: Fri, 3 Feb 2017 14:59:38 -0800
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Subject: [PATCH] tcp: avoid infinite loop in tcp_splice_read()
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Splicing from TCP socket is vulnerable when a packet with URG flag is
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received and stored into receive queue.
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__tcp_splice_read() returns 0, and sk_wait_data() immediately
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returns since there is the problematic skb in queue.
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This is a nice way to burn cpu (aka infinite loop) and trigger
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soft lockups.
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Again, this gem was found by syzkaller tool.
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Fixes: 9c55e01c0cc8 ("[TCP]: Splice receive support.")
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Reported-by: Dmitry Vyukov <dvyukov@google.com>
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Cc: Willy Tarreau <w@1wt.eu>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv4/tcp.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
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index 4a044964da667..0efb4c7f6704f 100644
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--- a/net/ipv4/tcp.c
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+++ b/net/ipv4/tcp.c
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@@ -770,6 +770,12 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
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ret = -EAGAIN;
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break;
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}
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+ /* if __tcp_splice_read() got nothing while we have
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+ * an skb in receive queue, we do not want to loop.
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+ * This might happen with URG data.
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+ */
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+ if (!skb_queue_empty(&sk->sk_receive_queue))
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+ break;
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sk_wait_data(sk, &timeo, NULL);
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if (signal_pending(current)) {
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ret = sock_intr_errno(timeo);
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