On Thu, Nov 22, 2012 at 03:21:31PM +0200, 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@xxxxxxxxx>
> ---
> 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);
> --
> 1.7.9.5
>
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>
I'm fine with it the way it is, but it might be nicer if you instead just moved
the list_add_tail call up between the if (!chunk) check and the
sctp_user_addto_chunk call. That way the unwind loop at the errout label can
just free the chunk without the need for an extra label.
Neil
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