diff mbox

[PULL,03/24] qcow2: Check bs->drv in copy_sectors()

Message ID 1394620172-25071-4-git-send-email-stefanha@redhat.com
State New
Headers show

Commit Message

Stefan Hajnoczi March 12, 2014, 10:29 a.m. UTC 
From: Max Reitz <mreitz@redhat.com>

Before dereferencing bs->drv for a call to its member bdrv_co_readv(),
copy_sectors() should check whether that pointer is indeed valid, since
it may have been set to NULL by e.g. a concurrent write triggering the
corruption prevention mechanism.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/qcow2-cluster.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 36c1bed..9499df9 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -380,6 +380,10 @@  static int coroutine_fn copy_sectors(BlockDriverState *bs,
 
     BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
 
+    if (!bs->drv) {
+        return -ENOMEDIUM;
+    }
+
     /* Call .bdrv_co_readv() directly instead of using the public block-layer
      * interface.  This avoids double I/O throttling and request tracking,
      * which can lead to deadlock when block layer copy-on-read is enabled.