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Re: [Qemu-devel] [PATCH v2] vhost: Fix use-after-free in vhost_log_put()
From: |
Marc-André Lureau |
Subject: |
Re: [Qemu-devel] [PATCH v2] vhost: Fix use-after-free in vhost_log_put() |
Date: |
Fri, 30 Jun 2017 12:07:57 +0000 |
On Fri, Jun 30, 2017 at 2:03 PM Jia-Shiun Li <address@hidden> wrote:
> In commit 9e0bc24f dev->log_size was reset to zero too early before
> syncing vhost log. It causes syncing to be skipped.
>
> Use local variable to keep its value before resetting.
>
> Signed-off-by: Jia-Shiun Li <address@hidden>
>
Reviewed-by: Marc-André Lureau <address@hidden>
---
>
> v1 -> v2:
> * Use local variable to keep value of dev->log_size.
>
> ---
> hw/virtio/vhost.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 6eddb09..c1c5714 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -371,6 +371,7 @@ static struct vhost_log *vhost_log_get(uint64_t size,
> bool share)
> static void vhost_log_put(struct vhost_dev *dev, bool sync)
> {
> struct vhost_log *log = dev->log;
> + uint64_t log_size = dev->log_size;
>
> if (!log) {
> return;
> @@ -381,8 +382,8 @@ static void vhost_log_put(struct vhost_dev *dev, bool
> sync)
> --log->refcnt;
> if (log->refcnt == 0) {
> /* Sync only the range covered by the old log */
> - if (dev->log_size && sync) {
> - vhost_log_sync_range(dev, 0, dev->log_size * VHOST_LOG_CHUNK
> - 1);
> + if (log_size && sync) {
> + vhost_log_sync_range(dev, 0, log_size * VHOST_LOG_CHUNK - 1);
> }
>
> if (vhost_log == log) {
> --
> 2.7.4
>
> --
Marc-André Lureau