The sctp_asoc_get_hmac() function iterates through a peer's hmac_ids
array and attempts to ensure that only a supported hmac entry is
returned. The current code fails to do this properly - if the last id
in the array is out of range (greater than SCTP_AUTH_HMAC_ID_MAX), the
id integer remains set after exiting the loop, and the address of an
out-of-bounds entry will be returned and subsequently used in the parent
function, causing potentially ugly memory corruption. This patch resets
the id integer to 0 on encountering an invalid id so that NULL will be
returned after finishing the loop if no valid ids are found.
Signed-off-by: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
--- linux-2.6.35.5.orig/net/sctp/auth.c 2010-09-20 16:59:09.000000000 -0400
+++ linux-2.6.35.5/net/sctp/auth.c 2010-10-01 16:48:58.000000000 -0400
@@ -543,16 +543,20 @@ struct sctp_hmac *sctp_auth_asoc_get_hma
id = ntohs(hmacs->hmac_ids[i]);
/* Check the id is in the supported range */
- if (id > SCTP_AUTH_HMAC_ID_MAX)
+ if (id > SCTP_AUTH_HMAC_ID_MAX) {
+ id = 0;
continue;
+ }
/* See is we support the id. Supported IDs have name and
* length fields set, so that we can allocated and use
* them. We can safely just check for name, for without the
* name, we can't allocate the TFM.
*/
- if (!sctp_hmac_list[id].hmac_name)
+ if (!sctp_hmac_list[id].hmac_name) {
+ id = 0;
continue;
+ }
break;
}
--
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