From: Dan Rosenberg Date: Fri, 1 Oct 2010 11:51:47 +0000 (+0000) Subject: sctp: Fix out-of-bounds reading in sctp_asoc_get_hmac() X-Git-Tag: v2.6.36-rc8~17^2~13 X-Git-Url: https://bbs.cooldavid.org/git/?p=net-next-2.6.git;a=commitdiff_plain;h=51e97a12bef19b7e43199fc153cf9bd5f2140362 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 Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- diff --git a/net/sctp/auth.c b/net/sctp/auth.c index 86366390038..ddbbf7c81fa 100644 --- a/net/sctp/auth.c +++ b/net/sctp/auth.c @@ -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; }