Miaoqing Pan 07246c1158 ath9k: fix an invalid pointer dereference in ath9k_rng_stop()
The bug was triggered when do suspend/resuming continuously
on Dell XPS L322X/0PJHXN version 9333 (2013) with kernel
4.12.0-041200rc4-generic. But can't reproduce on DELL
E5440 + AR9300 PCIE chips.

The warning is caused by accessing invalid pointer sc->rng_task.
sc->rng_task is not be cleared after kthread_stop(sc->rng_task)
be called in ath9k_rng_stop(). Because the kthread is stopped
before ath9k_rng_kthread() be scheduled.

So set sc->rng_task to null after kthread_stop(sc->rng_task) to
resolve this issue.

WARNING: CPU: 0 PID: 984 at linux/kernel/kthread.c:71 kthread_stop+0xf1/0x100
CPU: 0 PID: 984 Comm: NetworkManager Not tainted 4.12.0-041200rc4-generic #201706042031
Hardware name: Dell Inc.          Dell System XPS L322X/0PJHXN, BIOS A09 05/15/2013
task: ffff950170fdda00 task.stack: ffffa22c01538000
RIP: 0010:kthread_stop+0xf1/0x100
RSP: 0018:ffffa22c0153b5b0 EFLAGS: 00010246
RAX: ffffffffa6257800 RBX: ffff950171b79560 RCX: 0000000000000000
RDX: 0000000080000000 RSI: 000000007fffffff RDI: ffff9500ac9a9680
RBP: ffffa22c0153b5c8 R08: 0000000000000000 R09: 0000000000000000
R10: ffffa22c0153b648 R11: ffff9501768004b8 R12: ffff9500ac9a9680
R13: ffff950171b79f70 R14: ffff950171b78780 R15: ffff9501749dc018
FS:  00007f0d6bfd5540(0000) GS:ffff95017f200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc190161a08 CR3: 0000000232906000 CR4: 00000000001406f0
Call Trace:
  ath9k_rng_stop+0x1a/0x20 [ath9k]
  ath9k_stop+0x3b/0x1d0 [ath9k]
  drv_stop+0x33/0xf0 [mac80211]
  ieee80211_stop_device+0x43/0x50 [mac80211]
  ieee80211_do_stop+0x4f2/0x810 [mac80211]

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196043
Reported-by: Giulio Genovese <giulio.genovese@gmail.com>
Tested-by: Giulio Genovese <giulio.genovese@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
2017-06-28 19:54:33 +03:00
2017-05-08 17:15:12 -07:00
2017-06-22 11:35:19 -04:00
2017-06-15 12:12:40 -04:00
2017-06-19 22:19:37 +08:00

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
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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.
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