Re: [Qemu-devel] [PATCH V4] net/colo-compare.c: Fix memory leak and code style issue.

[Peter Maydell]

On Sun, 21 Jul 2019 at 10:04, Zhang Chen <address@hidden> wrote:
>
> From: Zhang Chen <address@hidden>
>
> This patch to fix the origin "char *data" memory leak, code style issue
> and add necessary check here.
> Reported-by: Coverity (CID 1402785)
>
> Signed-off-by: Zhang Chen <address@hidden>

> @@ -1008,21 +1019,24 @@ static void 
> compare_notify_rs_finalize(SocketReadState *notify_rs)
>  {
>      CompareState *s = container_of(notify_rs, CompareState, notify_rs);
>
> -    /* Get Xen colo-frame's notify and handle the message */
> -    char *data = g_memdup(notify_rs->buf, notify_rs->packet_len);
> -    char msg[] = "COLO_COMPARE_GET_XEN_INIT";
> +    const char msg[] = "COLO_COMPARE_GET_XEN_INIT";
>      int ret;
>
> -    if (!strcmp(data, "COLO_USERSPACE_PROXY_INIT")) {
> +    if (packet_matches_str("COLO_USERSPACE_PROXY_INIT",
> +                           notify_rs->buf,
> +                           notify_rs->packet_len)) {
>          ret = compare_chr_send(s, (uint8_t *)msg, strlen(msg), 0, true);
>          if (ret < 0) {
>              error_report("Notify Xen COLO-frame INIT failed");
>          }
> -    }
> -
> -    if (!strcmp(data, "COLO_CHECKPOINT")) {
> +    } else if (packet_matches_str("COLO_CHECKPOINT",
> +                                  notify_rs->buf,
> +                                  notify_rs->packet_len)) {
>          /* colo-compare do checkpoint, flush pri packet and remove sec 
> packet */
>          g_queue_foreach(&s->conn_list, colo_flush_packets, s);
> +    } else {
> +        error_report("COLO compare got unsupported instruction '%s'",
> +                     (char *)notify_rs->buf);
>      }

The notify_rs->buf is not NUL-terminated, so you can't use it
in a %s format string like this. The simplest fix is just
to not try to print the contents of the incoming packet at all.

The rest of the patch looks good.

thanks
-- PMM