Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 06/32] tcp: fix 0 divide in __tcp_select_window() | Date | Thu, 16 Feb 2017 09:54:42 -0800 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 06425c308b92eaf60767bc71d359f4cbc7a561f8 ]
syszkaller fuzzer was able to trigger a divide by zero, when TCP window scaling is not enabled.
SO_RCVBUF can be used not only to increase sk_rcvbuf, also to decrease it below current receive buffers utilization.
If mss is negative or 0, just return a zero TCP window.
Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/tcp_output.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2436,9 +2436,11 @@ u32 __tcp_select_window(struct sock *sk) int full_space = min_t(int, tp->window_clamp, allowed_space); int window; - if (mss > full_space) + if (unlikely(mss > full_space)) { mss = full_space; - + if (mss <= 0) + return 0; + } if (free_space < (full_space >> 1)) { icsk->icsk_ack.quick = 0;
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