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Re: [Qemu-devel] [Qemu-trivial] [PATCH v6 03/10] virtio-blk: fix referen
From: |
Michael Tokarev |
Subject: |
Re: [Qemu-devel] [Qemu-trivial] [PATCH v6 03/10] virtio-blk: fix reference a pointer which might be freed |
Date: |
Mon, 18 Aug 2014 15:49:22 +0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.7.0 |
14.08.2014 11:29, zhanghailiang wrote:
> In function virtio_blk_handle_request, it may freed memory pointed by req,
> So do not access member of req after calling this function.
>
> Reviewed-by: Stefan Hajnoczi <address@hidden>
> Signed-off-by: zhanghailiang <address@hidden>
> ---
> hw/block/virtio-blk.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index c241c50..54a853a 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -458,7 +458,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev,
> VirtQueue *vq)
> static void virtio_blk_dma_restart_bh(void *opaque)
> {
> VirtIOBlock *s = opaque;
> - VirtIOBlockReq *req = s->rq;
> + VirtIOBlockReq *req = s->rq, *next = NULL;
> MultiReqBuffer mrb = {
> .num_writes = 0,
> };
> @@ -469,8 +469,9 @@ static void virtio_blk_dma_restart_bh(void *opaque)
> s->rq = NULL;
>
> while (req) {
> + next = req->next;
> virtio_blk_handle_request(req, &mrb);
> - req = req->next;
> + req = next;
> }
>
> virtio_submit_multiwrite(s->bs, &mrb);
So, finally, I've applied this patch:
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -469,8 +469,9 @@ static void virtio_blk_dma_restart_bh(void *opaque)
s->rq = NULL;
while (req) {
+ VirtIOBlockReq *next = req->next;
virtio_blk_handle_request(req, &mrb);
- req = req->next;
+ req = next;
}
virtio_submit_multiwrite(s->bs, &mrb);
and dropped Stefan's Reviewed-by on the way ;)
This is a bugfix after all ;)
Thanks,
/mjt
- Re: [Qemu-devel] [PATCH v6 07/10] linux-user: check return value of malloc(), (continued)
[Qemu-devel] [PATCH v6 09/10] tcg: check return value of fopen(), zhanghailiang, 2014/08/14
[Qemu-devel] [PATCH v6 02/10] monitor: fix access freed memory, zhanghailiang, 2014/08/14