sctp: correct bounds check in sctp_setsockopt_auth_key

The bonds check to prevent buffer overlflow was not exactly
right.  It still allowed overflow of up to 8 bytes which is
sizeof(struct sctp_authkey).

Since optlen is already checked against the size of that struct,
we are guaranteed not to cause interger overflow either.

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

1 files changed, 1 insertions, 1 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index afa952e726d7..9b9b2c31dd15 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -3144,7 +3144,7 @@ static int sctp_setsockopt_auth_key(struct sock *sk,
                 goto out;
         }
 
-        if (authkey->sca_keylength > optlen) {
+        if (authkey->sca_keylength > optlen - sizeof(struct sctp_authkey)) {
                 ret = -EINVAL;
                 goto out;
         }