[Qemu-devel] [PATCH v2 3/4] virtio-blk: fix reference a pointer which might be freed

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

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 <stefanha@redhat.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 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);
-- 
1.7.12.4