sctp: fix the length check in sctp_getsockopt_maxburst()

The code in sctp_getsockopt_maxburst() doesn't allow len to be larger
then struct sctp_assoc_value, which is a common case where app writers
just pass down the sizeof(buf) or something similar.

This patch fix the problem.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 4bc558c19fcf..bbd3cd238d7f 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5286,7 +5286,8 @@ static int sctp_getsockopt_maxburst(struct sock *sk, int len,
                 printk(KERN_WARNING
                    "SCTP: Use struct sctp_assoc_value instead\n");
                 params.assoc_id = 0;
-        } else if (len == sizeof (struct sctp_assoc_value)) {
+        } else if (len >= sizeof(struct sctp_assoc_value)) {
+                len = sizeof(struct sctp_assoc_value);
                 if (copy_from_user(&params, optval, len))
                         return -EFAULT;
         } else