[patch 15/16] sctp: fix random memory dereference with SCTP_HMAC_IDENT option.

[Greg KH <gregkh@suse.de>]

[-- Attachment #1: 0012-sctp-fix-random-memory-dereference-with-SCTP_HMAC_I.patch --]
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2.6.25-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Vlad Yasevich <vladislav.yasevich@hp.com>

[ Upstream commit d97240552cd98c4b07322f30f66fd9c3ba4171de ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/sctp/auth.c   |    3 +++
 net/sctp/socket.c |    6 ++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

--- a/net/sctp/auth.c
+++ b/net/sctp/auth.c
@@ -786,6 +786,9 @@ int sctp_auth_ep_set_hmacs(struct sctp_e
 	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;
 
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -3014,6 +3014,7 @@ static int sctp_setsockopt_hmac_ident(st
 				    int optlen)
 {
 	struct sctp_hmacalgo *hmacs;
+	u32 idents;
 	int err;
 
 	if (!sctp_auth_enable)
@@ -3031,8 +3032,9 @@ static int sctp_setsockopt_hmac_ident(st
 		goto out;
 	}
 
-	if (hmacs->shmac_num_idents == 0 ||
-	    hmacs->shmac_num_idents > SCTP_AUTH_NUM_HMACS) {
+	idents = hmacs->shmac_num_idents;
+	if (idents == 0 || idents > SCTP_AUTH_NUM_HMACS ||
+	    (idents * sizeof(u16)) > (optlen - sizeof(struct sctp_hmacalgo))) {
 		err = -EINVAL;
 		goto out;
 	}

--