Pkg xen devel - Jul 2017 - Bug#870007: blktap-2.0.93: blktap (blktap-2.0.93) kernel module crashes when the blktap_device_create() function is invoked.

Package: blktap-dkms
Version: 2.0.93-0.8
Severity: important
File: blktap-2.0.93

Dear Maintainer,

   * What led up to the situation?
        I installed debain kernel(Linux 4.9.0-0.bpo.3-amd64 SMP Debian
4.9.30-2+deb9u2~bpo8+1 x86_64 GNU/Linux) on my machine and installed
xen(4.8.1). Also, installed blktap-2.0.93 and configured xen to use it. The xen
guest creation was failing due to an error and I saw that the blktap kernel
module crashes whenever I tried to do so. When looked into it, I found a bug
which is present in the device.c source file (as part of a fix for debian
kernel).

   * What exactly did you do (or not do) that was effective (or
     ineffective)?
        dev_info() invoked inside blktap_device_create() function within
device.c is what causes the crash. The last parameter passed to the function
(i.e.,
test_bit(QUEUE_FLAG_WC, rq->queue_flags)) is the reason why it crashes.
Because, the second argument passed to the test_bit() function is required to
be a pointer whereas rq->queue_flags is of type unsigned integer.
Passing the address instead fixes the issue.
This also seems like a valid fix (though the format string could be better):
https://github.com/OpenXT/xenclient-oe/blob/master/recipes-
kernel/linux/4.9/patches/blktap2.patch#L1229

   * What was the outcome of this action?
        Xen was unable to create a tapdisk because of the above problem, after
fix the this issue was resolved.

   * What outcome did you expect instead?
        After my fix, the outcome was as expected.



-- System Information:
Debian Release: 8.8
  APT prefers oldstable-updates
  APT policy: (500, 'oldstable-updates'), (500, 'oldstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-0.bpo.3-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages blktap-dkms depends on:
ii  dkms            2.3-2~bpo8+1
ii  libc6-dev       2.19-18+deb8u10
ii  linux-libc-dev  4.9.30-2+deb9u2~bpo8+1

Versions of packages blktap-dkms recommends:
ii  linux-headers-amd64  4.9+80~bpo8+1

blktap-dkms suggests no packages.

Your message dated Sat, 29 Jul 2017 09:48:52 +0000
with message-id <E1dbOMe-0002nn-5C at fasolo.debian.org>
and subject line Bug#870007: fixed in blktap-dkms 2.0.93-0.9
has caused the Debian Bug report #870007,
regarding blktap-2.0.93: blktap (blktap-2.0.93) kernel module crashes when the
blktap_device_create() function is invoked.
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner at bugs.debian.org
immediately.)


-- 
870007: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=870007
Debian Bug Tracking System
Contact owner at bugs.debian.org with problems
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Subject: blktap-2.0.93: blktap (blktap-2.0.93) kernel module crashes when the
blktap_device_create() function is invoked.
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Subject: Bug#870007: fixed in blktap-dkms 2.0.93-0.9
Date: Sat, 29 Jul 2017 09:48:52 +0000
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