Created attachment 1448350 [details]
Compressed corrupted qcow2 image

Description of problem:

qemu’s qcow2 driver does not consider whether an image is inactive when marking it corrupt.  This results in an assertion failure because inactive images may not be written to.


Version-Release number of selected component (if applicable):

Upstream (2.12.50), and in RHV (qemu-kvm-rhev-2.12.0-3.el7).

(RHEL (1.5.3) is not directly affected because there is no assertion preventing writes to inactive disks.  We should not try to write to it anyway, but at least it does not cause a VM crash.)


How reproducible:

Always.


Steps to Reproduce:
1. Download the attached qcow2 file and place it in your working directory.
2. Execute the following:
$ echo -e 'qemu-io none0 "read 0 64k"\nquit' \
    | qemu-system-x86_64 -drive if=none,file=corrupted.qcow2 \
                         -monitor stdio \
                         -incoming exec:'cat /dev/null'

Actual results:

QEMU 2.12.0 monitor - type 'help' for more information
(qemu) qemu-io none0 "read 0 64k"
qcow2: Marking image as corrupt: L2 table offset 0x44200 unaligned (L1 index: 0); further corruption events will be suppressed
qemu-system-x86_64: block/io.c:1682: bdrv_co_pwritev: Assertion `!(bs->open_flags & BDRV_O_INACTIVE)' failed.
[1]    16427 done                 echo 'qemu-io none0 "read 0 64k"' | 
       16428 abort (core dumped)  qemu-system-x86_64 -drive if=none,file=corrupted.qcow2 -monito


Expected results:

QEMU 2.12.0 monitor - type 'help' for more information
(qemu) qemu-io none0 "read 0 64k"
qcow2: Image is corrupt: L2 table offset 0x44200 unaligned (L1 index: 0); further non-fatal corruption events will be suppressed
read failed: Input/output error
(qemu) quit

(The qcow2 driver does not try to mark the image corrupt (as if it were read-only), and thus, no crash occurs.)


Additional info:

Noticed in the logs for BZ 1583346.