tcp: Add TCP_USER_TIMEOUT negative value check

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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 581ecf02c6b5..e7e6eeae49c0 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2681,7 +2681,10 @@ 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;