Commit 51e97a12 authored Oct 01, 2010 by Dan Rosenberg Committed by David S. Miller Oct 03, 2010

sctp: Fix out-of-bounds reading in sctp_asoc_get_hmac()

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

parent d7e0d19a

net/sctp/auth.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -543,16 +543,20 @@ struct sctp_hmac sctp_auth_asoc_get_hmac(const struct sctp_association asoc)
		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;
		}