On 09/03/2010 09:48 AM, Dan Rosenberg wrote:
> Two user-controlled allocations in SCTP are subsequently dereferenced
> as sockaddr structs, without checking if the dereferenced struct
> members fall beyond the end of the allocated chunk. There doesn't
> appear to be any information leakage here based on how these members
> are used and additional checking, but it's still worth fixing.
>
> Signed-off-by: Dan Rosenberg <dan.j.rosenberg@xxxxxxxxx>
>
> --- linux-2.6.35.4.orig/net/sctp/socket.c 2010-09-03 08:58:48.127080114 -0400
> +++ linux-2.6.35.4/net/sctp/socket.c 2010-09-03 09:22:06.337096825 -0400
> @@ -889,6 +889,7 @@ SCTP_STATIC int sctp_setsockopt_bindx(st
> int err;
> int addrcnt = 0;
> int walk_size = 0;
> + unsigned int remaining = addrs_size;
> struct sockaddr *sa_addr;
> void *addr_buf;
> struct sctp_af *af;
> @@ -916,6 +917,13 @@ SCTP_STATIC int sctp_setsockopt_bindx(st
> /* Walk through the addrs buffer and count the number of addresses. */
> addr_buf = kaddrs;
> while (walk_size < addrs_size) {
> +
> + /* Don't read out-of-bounds memory */
> + if (remaining < sizeof(struct sockaddr)) {
> + kfree(kaddrs);
> + return -EINVAL;
> + }
> +
Hm.. we already validate that we have the proper amount of space for a given sockaddr.
The only thing we are missing is making sure that there is room to get the proper address
family and I think you can do that without adding any extra variables:
if (walk_size + sizeof(sa_family_t) > addr_size) {
/* Not enough room for address family */
kfree(kaddrs);
return -EINVAL;
}
-vlad
> sa_addr = (struct sockaddr *)addr_buf;
> af = sctp_get_af_specific(sa_addr->sa_family);
>
> @@ -929,6 +937,7 @@ SCTP_STATIC int sctp_setsockopt_bindx(st
> addrcnt++;
> addr_buf += af->sockaddr_len;
> walk_size += af->sockaddr_len;
> + remaining -= af->sockaddr_len;
> }
>
> /* Do the work. */
> @@ -984,6 +993,7 @@ static int __sctp_connect(struct sock* s
> void *addr_buf;
> unsigned short port;
> unsigned int f_flags = 0;
> + unsigned int remaining = addrs_size;
>
> sp = sctp_sk(sk);
> ep = sp->ep;
> @@ -1002,6 +1012,13 @@ static int __sctp_connect(struct sock* s
> /* Walk through the addrs buffer and count the number of addresses. */
> addr_buf = kaddrs;
> while (walk_size < addrs_size) {
> +
> + /* Don't read out-of-bounds memory */
> + if (remaining < sizeof(union sctp_addr)) {
> + err = -EINVAL;
> + goto out_free;
> + }
> +
> sa_addr = (union sctp_addr *)addr_buf;
> af = sctp_get_af_specific(sa_addr->sa.sa_family);
> port = ntohs(sa_addr->v4.sin_port);
> @@ -1101,6 +1118,7 @@ static int __sctp_connect(struct sock* s
> addrcnt++;
> addr_buf += af->sockaddr_len;
> walk_size += af->sockaddr_len;
> + remaining -= af->sockaddr_len;
> }
>
> /* In case the user of sctp_connectx() wants an association
>
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