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Borislav Petkov fbc3edf7d7 drivers/ide-cd: Handle missing driver data during status check gracefully
The 0day bot reports the below failure which happens occasionally, with
their randconfig testing (once every ~100 boots).  The Code points at
the private pointer ->driver_data being NULL, which hints at a race of
sorts where the private driver_data descriptor has disappeared by the
time we get to run the workqueue.

So let's check that pointer before we continue with issuing the command
to the drive.

This fix is of the brown paper bag nature but considering that IDE is
long deprecated, let's do that so that random testing which happens to
enable CONFIG_IDE during randconfig builds, doesn't fail because of
this.

Besides, failing the TEST_UNIT_READY command because the drive private
data is gone is something which we could simply do anyway, to denote
that there was a problem communicating with the device.

  BUG: unable to handle kernel NULL pointer dereference at 000001c0
  IP: cdrom_check_status
  *pde = 00000000
  Oops: 0000 [#1] SMP
  CPU: 1 PID: 155 Comm: kworker/1:2 Not tainted 4.14.0-rc8 #127
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  Workqueue: events_freezable_power_ disk_events_workfn
  task: 4fe90980 task.stack: 507ac000
  EIP: cdrom_check_status+0x2c/0x90
  EFLAGS: 00210246 CPU: 1
  EAX: 00000000 EBX: 4fefec00 ECX: 00000000 EDX: 00000000
  ESI: 00000003 EDI: ffffffff EBP: 467a9340 ESP: 507aded0
   DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
  CR0: 80050033 CR2: 000001c0 CR3: 06e0f000 CR4: 00000690
  Call Trace:
   ? ide_cdrom_check_events_real
   ? cdrom_check_events
   ? disk_check_events
   ? process_one_work
   ? process_one_work
   ? worker_thread
   ? kthread
   ? process_one_work
   ? __kthread_create_on_node
   ? ret_from_fork
  Code: 53 83 ec 14 89 c3 89 d1 be 03 00 00 00 65 a1 14 00 00 00 89 44 24 10 31 c0 8b 43 18 c7 44 24 04 00 00 00 00 c7 04 24 00 00 00 00 <8a> 80 c0 01 00 00 c7 44 24 08 00 00 00 00 83 e0 03 c7 44 24 0c
  EIP: cdrom_check_status+0x2c/0x90 SS:ESP: 0068:507aded0
  CR2: 00000000000001c0
  ---[ end trace 2410e586dd8f88b2 ]---

Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-07 09:12:04 -08:00
arch Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-06 09:05:03 -08:00
block License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-06 09:05:03 -08:00
Documentation Documentation: enforcement-statement: name updates 2017-11-05 10:21:06 -08:00
drivers drivers/ide-cd: Handle missing driver data during status check gracefully 2017-11-07 09:12:04 -08:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs fs/hugetlbfs/inode.c: fix hwpoison reserve accounting 2017-11-03 07:39:19 -07:00
include Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-05 11:44:39 -08:00
init License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2017-11-06 12:26:49 -08:00
lib License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
mm mm, swap: fix race between swap count continuation operations 2017-11-03 07:39:19 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-03 09:09:21 -07:00
samples License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
scripts scripts: add leaking_addresses.pl 2017-11-06 11:46:42 -08:00
security License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
sound License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-05 11:44:39 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt Fixes for interrupt controller emulation in ARM/ARM64 and x86, plus a one-liner 2017-11-04 11:44:55 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap Update MIPS email addresses 2017-11-03 09:02:30 -07:00
COPYING
CREDITS selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS scripts: add leaking_addresses.pl 2017-11-06 11:46:42 -08:00
Makefile Linux 4.14-rc8 2017-11-05 13:05:14 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.