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authorEric Dumazet <edumazet@google.com>2017-02-01 08:33:53 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-18 15:11:41 +0100
commitca876dff1e8c04871d019c57016514df4cf04a25 (patch)
treebf317aaf5e4a40fcc33b8befb65a54245e452517 /net/ipv4
parente6fbace87c7b57ff6143df2bc18a9ca9ae919bbe (diff)
tcp: fix 0 divide in __tcp_select_window()
[ 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>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_output.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 896e9dfbdb5c..65d6189140bc 100644
--- 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;