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Re: [Qemu-devel] [PULL 16/17] COLO-compare: Add colo-compare remote noti
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PULL 16/17] COLO-compare: Add colo-compare remote notify support |
Date: |
Tue, 2 Jul 2019 19:51:22 +0100 |
On Tue, 2 Jul 2019 at 03:32, Jason Wang <address@hidden> wrote:
>
> From: Zhang Chen <address@hidden>
>
> This patch make colo-compare can send message to remote COLO frame(Xen) when
> occur checkpoint.
>
> Signed-off-by: Zhang Chen <address@hidden>
> Signed-off-by: Jason Wang <address@hidden>
Hi; Coverity reports a problem (CID 1402785) with this function:
> @@ -989,7 +1006,24 @@ static void compare_sec_rs_finalize(SocketReadState
> *sec_rs)
>
> 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";
> + int ret;
> +
> + if (!strcmp(data, "COLO_USERSPACE_PROXY_INIT")) {
> + 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")) {
> + /* colo-compare do checkpoint, flush pri packet and remove sec
> packet */
> + g_queue_foreach(&s->conn_list, colo_flush_packets, s);
> + }
> }
We allocate data using g_memdup(), but we never free it before returning,
so the function has a memory leak. It's not clear to me why we're
duplicating the string at all -- it would be cleaner to do the
check of the packet contents to identify in-place. That would be
the best way to fix/avoid the leak.
Some other things I notice reading the function:
(1) after the first if() we will go ahead and check the second if().
This means we'll unnecessarily check whether the data string
matches COLO_CHECKPOINT, when we know already it cannot. I think
an if (!strcmp(...)) { ... } else if (!strcmp(...)) { ... }
structure would be more normal C here.
(2) the g_memdup() call is treating the data as a buffer-and-length,
and we don't enforce that it is NUL-terminated. But then we do a
strcmp() against it, which assumes that the data is a NUL-terminated
string. Is this safe ?
(3) More minor point: you could mark 'msg' as const here, since
I think we never need to modify it.
thanks
-- PMM
- [Qemu-devel] [PULL 02/17] qemu-bridge-helper: Document known shortcomings, (continued)
- [Qemu-devel] [PULL 02/17] qemu-bridge-helper: Document known shortcomings, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 09/17] net/announce: Add HMP optional interface list, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 05/17] net: avoid using variable length array in net_client_init(), Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 10/17] net/announce: Add optional ID, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 11/17] net/announce: Add HMP optional ID, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 12/17] net/announce: Expand test for stopping self announce, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 13/17] COLO-compare: Add new parameter to communicate with remote colo-frame, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 14/17] COLO-compare: Add remote notification chardev handler frame, Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 15/17] COLO-compare: Make the compare_chr_send() can send notification message., Jason Wang, 2019/07/01
- [Qemu-devel] [PULL 16/17] COLO-compare: Add colo-compare remote notify support, Jason Wang, 2019/07/01
- Re: [Qemu-devel] [PULL 16/17] COLO-compare: Add colo-compare remote notify support,
Peter Maydell <=
- [Qemu-devel] [PULL 17/17] migration/colo.c: Add missed filter notify for Xen COLO., Jason Wang, 2019/07/01
- Re: [Qemu-devel] [PULL 00/17] Net patches, Peter Maydell, 2019/07/02