Re: [PATCH] sctp: fix memory leak in sctp_datamsg_from_user() when copy from user space fails

[Vlad Yasevich <vyasevich@gmail.com>]

On 11/22/2012 08:21 AM, Tommi Rantala wrote:
> Trinity (the syscall fuzzer) discovered a memory leak in SCTP,
> reproducible e.g. with the sendto() syscall by passing invalid
> user space pointer in the second argument:
>
>   #include <string.h>
>   #include <arpa/inet.h>
>   #include <sys/socket.h>
>
>   int main(void)
>   {
>           int fd;
>           struct sockaddr_in sa;
>
>           fd = socket(AF_INET, SOCK_STREAM, 132 /*IPPROTO_SCTP*/);
>           if (fd < 0)
>                   return 1;
>
>           memset(&sa, 0, sizeof(sa));
>           sa.sin_family = AF_INET;
>           sa.sin_addr.s_addr = inet_addr("127.0.0.1");
>           sa.sin_port = htons(11111);
>
>           sendto(fd, NULL, 1, 0, (struct sockaddr *)&sa, sizeof(sa));
>
>           return 0;
>   }
>
> As far as I can tell, the leak has been around since ~2003.
>
> Signed-off-by: Tommi Rantala <tt.rantala@gmail.com>
> ---
>   net/sctp/chunk.c |    7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
> index 7c2df9c..d241ef5 100644
> --- a/net/sctp/chunk.c
> +++ b/net/sctp/chunk.c
> @@ -284,7 +284,7 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
>   			goto errout;
>   		err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
>   		if (err < 0)
> -			goto errout;
> +			goto errout_chunk_put;
>
>   		offset += len;
>
> @@ -324,7 +324,7 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
>   		__skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
>   			   - (__u8 *)chunk->skb->data);
>   		if (err < 0)
> -			goto errout;
> +			goto errout_chunk_put;
>
>   		sctp_datamsg_assign(msg, chunk);
>   		list_add_tail(&chunk->frag_list, &msg->chunks);
> @@ -332,6 +332,9 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
>
>   	return msg;
>
> +errout_chunk_put:
> +	sctp_chunk_put(chunk);
> +
>   errout:
>   	list_for_each_safe(pos, temp, &msg->chunks) {
>   		list_del_init(pos);
>

Should be using sctp_chunk_free().  Good find.

-vlad