Ha, I knew there was an easier way. Take two:
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 10:28:14.929595312 -0400
@@ -916,6 +916,12 @@ 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) {
+
+ if (walk_size + sizeof(sa_family_t) > addrs_size) {
+ kfree(kaddrs);
+ return -EINVAL;
+ }
+
sa_addr = (struct sockaddr *)addr_buf;
af = sctp_get_af_specific(sa_addr->sa_family);
@@ -1002,6 +1008,12 @@ 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) {
+
+ if (walk_size + sizeof(sa_family_t) > addrs_size) {
+ 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);
>
> 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
>
On Fri, Sep 3, 2010 at 10:15 AM, Vlad Yasevich
<vladislav.yasevich@xxxxxx> wrote:
> 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;
>> + }
>> +
>> 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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