Re: [Qemu-devel] [PATCH v2] net/colo-compare.c: Fix a crash in COLO Primary.

[Zhang, Chen]

> -----Original Message-----
> From: Lukas Straub [mailto:address@hidden
> Sent: Sunday, April 21, 2019 1:14 AM
> To: address@hidden
> Cc: Zhang, Chen <address@hidden>
> Subject: [PATCH v2] net/colo-compare.c: Fix a crash in COLO Primary.
> 
> From: Lukas Straub <address@hidden> Because event_unhandled_count
> may be accessed concurrently, it needs to be protected by taking the lock.
> However the assert is outside the lock, probably causing it to read garbage 
> and
> aborting Qemu erroneously.
> 
> The Bug only happens when running Qemu in COLO mode.
> 
> This Patch fixes the following bug:
> https://bugs.launchpad.net/qemu/+bug/1824622
> 
> Signed-off-by: Lukas Straub <address@hidden>

Looks good for me.

Reviewed-by: Zhang Chen <address@hidden>

Thanks
Zhang Chen

> ---
>  net/colo-compare.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/net/colo-compare.c b/net/colo-compare.c index
> bf10526f05..fcb491121b 100644
> --- a/net/colo-compare.c
> +++ b/net/colo-compare.c
> @@ -813,9 +813,8 @@ static void colo_compare_handle_event(void *opaque)
>          break;
>      }
> 
> -    assert(event_unhandled_count > 0);
> -
>      qemu_mutex_lock(&event_mtx);
> +    assert(event_unhandled_count > 0);
>      event_unhandled_count--;
>      qemu_cond_broadcast(&event_complete_cond);
>      qemu_mutex_unlock(&event_mtx);
> --
> 2.20.1