[Xen-changelog] [qemu-xen-3.4-testing] check for bs->drv in bdrv_flush (Christoph Hellwig)

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

commit b5e7982ade668d18e07f51401d9af04d612c3be3
Author: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Date:   Wed Oct 7 15:51:55 2009 +0100

    check for bs->drv in bdrv_flush (Christoph Hellwig)
    
    All the bdrv_ helpers should check for bs->drv being zero as that means
    there is no backend image open.  bdrv_flush fails to perform that check
    and can thus cause NULL pointer dereferences.
    
    Found using qemu-io.
    
    Signed-off-by: Christoph Hellwig <hch@xxxxxx>
    Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>
    
    git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6943 
c046a42c-6fe2-441c-8c8c-71466251a162
    
    [ Backported from 6bbff9a0b495918309074ac60375be5f9dc868b3
      by Stefano Stabellini. ]
    
    Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    (cherry picked from commit dddf85563a18db9ae83d59ad567f4d77d39da821)
---
 block.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/block.c b/block.c
index c3c44a9..3261225 100644
--- a/block.c
+++ b/block.c
@@ -1071,6 +1071,8 @@ const char *bdrv_get_device_name(BlockDriverState *bs)
 int bdrv_flush(BlockDriverState *bs)
 {
     int ret = 0;
+    if (!bs->drv)
+        return -EINVAL;
     if (bs->drv->bdrv_flush)
         ret = bs->drv->bdrv_flush(bs);
     if (!ret && bs->backing_hd)
--
generated by git-patchbot for /home/xen/git/qemu-xen-3.4-testing.git

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