sctp: fix random memory dereference with SCTP_HMAC_IDENT option.

The number of identifiers needs to be checked against the option
length.  Also, the identifier index provided needs to be verified
to make sure that it doesn't exceed the bounds of the array.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/net/sctp/auth.c b/net/sctp/auth.c
index 1fcb4cf2f4c9..52db5f60daa0 100644
--- a/net/sctp/auth.c
+++ b/net/sctp/auth.c
@@ -786,6 +786,9 @@ int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
         for (i = 0; i < hmacs->shmac_num_idents; i++) {
                 id = hmacs->shmac_idents[i];
 
+                if (id > SCTP_AUTH_HMAC_ID_MAX)
+                        return -EOPNOTSUPP;
+
                 if (SCTP_AUTH_HMAC_ID_SHA1 == id)
                         has_sha1 = 1;