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blockdev: check dinfo ptr before using

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If a user decides to punish a guest by revoking its block device via
drive_del, and subsequently also attempts to remove the pci device
backing it, and the device is using blockdev_auto_del() then we get a
segfault when we attempt to access dinfo->auto_del.[1]

The fix is to check if drive_get_by_blockdev() actually returns a valid
dinfo pointer or not.

1. (qemu) pci_add auto storage file=images/test01.raw,if=virtio,id=block1,snapshot=on
   (qemu) drive_del block1
   (qemu) pci_del 5
   *segfault*

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Ryan Harper 2010-12-08 10:05:00 -06:00 committed by Kevin Wolf
parent 9d861fa595
commit 0fc0f1fa7f
1 changed files with 4 additions and 2 deletions
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6
blockdev.c
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@ -30,14 +30,16 @@ void blockdev_mark_auto_del(BlockDriverState *bs)
{
DriveInfo *dinfo = drive_get_by_blockdev(bs);
dinfo->auto_del = 1;
if (dinfo) {
dinfo->auto_del = 1;
}
}
void blockdev_auto_del(BlockDriverState *bs)
{
DriveInfo *dinfo = drive_get_by_blockdev(bs);
if (dinfo->auto_del) {
if (dinfo && dinfo->auto_del) {
drive_uninit(dinfo);
}
}