[CRIU] [PATCH] sk-queue: Use int values in getsockopt

[Stanislav Kinsbursky]

13.07.2012 17:57, Cyrill Gorcunov пишет:
> The kernel threats them as interger values so
> we should declare them this way. Moreover, explicitly
> clean them up to eliminate side effects.
>
> Initially I hit a problem where high bits of long "size"
> variable was containing some crap from stack and in result
> I've got errors like
>
>   | Error (sk-queue.c:102): dump_sk_queue: Can't allocate 171798904800 bytes
>   | Error (cr-dump.c:1289): Dump files (pid: 2505) failed with -1
>

That's strange...
It looks like kernel bug...
BTW, here is a part of sock_getsockopt():

int sock_getsockopt(struct socket *sock, int level, int optname,
                     char __user *optval, int __user *optlen)
{
         struct sock *sk = sock->sk;

         union {
                 int val;
                 struct linger ling;
                 struct timeval tm;
         } v;

<--- SNIP --->

         memset(&v, 0, sizeof(v));	<=== Doesnt' we zeroing 8 bytes here?

<--- SNIP --->

         case SO_PEEK_OFF:
                 if (!sock->ops->set_peek_off)
                         return -EOPNOTSUPP;

                 v.val = sk->sk_peek_off;
                 break;




> Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> ---
>   sk-queue.c |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/sk-queue.c b/sk-queue.c
> index 7c29037..c849951 100644
> --- a/sk-queue.c
> +++ b/sk-queue.c
> @@ -59,14 +59,14 @@ int read_sk_queues(void)
>   int dump_sk_queue(int sock_fd, int sock_id)
>   {
>   	struct sk_packet_entry *pe;
> -	unsigned long size;
> +	int ret, size, orig_peek_off;
>   	socklen_t tmp;
> -	int ret, orig_peek_off;
>
>   	/*
>   	 * Save original peek offset.
>   	 */
>   	tmp = sizeof(orig_peek_off);
> +	orig_peek_off = 0;
>   	ret = getsockopt(sock_fd, SOL_SOCKET, SO_PEEK_OFF, &orig_peek_off, &tmp);
>   	if (ret < 0) {
>   		pr_perror("getsockopt failed\n");
> @@ -76,6 +76,7 @@ int dump_sk_queue(int sock_fd, int sock_id)
>   	 * Discover max DGRAM size
>   	 */
>   	tmp = sizeof(size);
> +	size = 0;
>   	ret = getsockopt(sock_fd, SOL_SOCKET, SO_SNDBUF, &size, &tmp);
>   	if (ret < 0) {
>   		pr_perror("getsockopt failed\n");
>


-- 
Best regards,
Stanislav Kinsbursky