[ 08/37] tcp: Add TCP_USER_TIMEOUT negative value check

[Ben Hutchings]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hangbin Liu <liuhangbin@xxxxxxxxx>

[ Upstream commit 42493570100b91ef663c4c6f0c0fdab238f9d3c2 ]

TCP_USER_TIMEOUT is a TCP level socket option that takes an unsigned int. But
patch "tcp: Add TCP_USER_TIMEOUT socket option"(dca43c75) didn't check the negative
values. If a user assign -1 to it, the socket will set successfully and wait
for 4294967295 miliseconds. This patch add a negative value check to avoid
this issue.

Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/ipv4/tcp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 11ba922..ad466a7 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2391,7 +2391,10 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 		/* Cap the max timeout in ms TCP will retry/retrans
 		 * before giving up and aborting (ETIMEDOUT) a connection.
 		 */
-		icsk->icsk_user_timeout = msecs_to_jiffies(val);
+		if (val < 0)
+			err = -EINVAL;
+		else
+			icsk->icsk_user_timeout = msecs_to_jiffies(val);
 		break;
 	default:
 		err = -ENOPROTOOPT;


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