From: Ryan Harper <ryanh@us.ibm.com>
Date: Mon, 7 Mar 2011 16:01:04 +0000 (-0600)
Subject: Don't allow multiwrites against a block device without underlying medium
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=301db7c2dd769d48e97c9a766520f8affff76cd7;p=qemu.git

Don't allow multiwrites against a block device without underlying medium

If the block device has been closed, we no longer have a medium to submit
IO against, check for this before submitting io.  This prevents a segfault
further in the code where we dereference elements of the block driver.

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---

diff --git a/block.c b/block.c
index 0559d835a2..c8e2f97614 100644
--- a/block.c
+++ b/block.c
@@ -2398,6 +2398,14 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
     MultiwriteCB *mcb;
     int i;
 
+    /* don't submit writes if we don't have a medium */
+    if (bs->drv == NULL) {
+        for (i = 0; i < num_reqs; i++) {
+            reqs[i].error = -ENOMEDIUM;
+        }
+        return -1;
+    }
+
     if (num_reqs == 0) {
         return 0;
     }