[PATCH 3.13.y-ckt 26/30] ALSA: dummy: Disable switching timer backend via sysfs

From	Kamal Mostafa <kamal@canonical.com>
Newsgroups	linux.kernel
Subject	[PATCH 3.13.y-ckt 26/30] ALSA: dummy: Disable switching timer backend via sysfs
Date	2016-02-10 22:50 +0100
Message-ID	<r0KO7-7Qy-37@gated-at.bofh.it> (permalink)
References	<r0KO5-7Qy-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

3.13.11-ckt35 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Takashi Iwai <tiwai@suse.de>

commit 7ee96216c31aabe1eb42fb91ff50dae9fcd014b2 upstream.

ALSA dummy driver can switch the timer backend between system timer
and hrtimer via its hrtimer module option.  This can be also switched
dynamically via sysfs, but it may lead to a memory corruption when
switching is done while a PCM stream is running; the stream instance
for the newly switched timer method tries to access the memory that
was allocated by another timer method although the sizes differ.

As the simplest fix, this patch just disables the switch via sysfs by
dropping the writable bit.

BugLink: http://lkml.kernel.org/r/CACT4Y+ZGEeEBntHW5WHn2GoeE0G_kRrCmUh6=dWyy-wfzvuJLg@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 sound/drivers/dummy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index 915b4d7..f4d626c 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -87,7 +87,7 @@ MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-128) for dummy driver.");
 module_param(fake_buffer, bool, 0444);
 MODULE_PARM_DESC(fake_buffer, "Fake buffer allocations.");
 #ifdef CONFIG_HIGH_RES_TIMERS
-module_param(hrtimer, bool, 0644);
+module_param(hrtimer, bool, 0444);
 MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
 #endif
 
-- 
1.9.1

Thread

[3.13.y-ckt stable] Linux 3.13.11-ckt35 stable review Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 26/30] ALSA: dummy: Disable switching timer backend via sysfs Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 30/30] powerpc/perf: Remove PPMU_HAS_SSLOT flag for Power8 Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 20/30] USB: option: fix Cinterion AHxx enumeration Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 27/30] drm/vmwgfx: respect 'nomodeset' Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 18/30] ALSA: seq: Degrade the error message for too many opens Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 10/30] usb: cdc-acm: handle unlinked urb in acm read callback Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 07/30] qeth: initialize net_device with carrier off Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 05/30] USB: serial: visor: fix crash on detecting device without write_urbs Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 09/30] x86/irq: Call chip->irq_set_affinity in proper context Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 24/30] SCSI: fix crashes in sd and sr runtime PM Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 06/30] ASN.1: Fix non-match detection failure on data overrun Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 22/30] ALSA: usb-audio: Fix TEAC UD-501/UD-503/NT-503 usb delay Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 17/30] ALSA: seq: Fix incorrect sanity check at snd_seq_oss_synth_cleanup() Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 14/30] USB: cp210x: add ID for IAI USB to RS485 adaptor Kamal Mostafa <kamal@canonical.com> - 2016-02-10 22:50 +0100
  [PATCH 3.13.y-ckt 02/30] [media] usbvision: fix leak of usb_dev on failure paths in usbvision_probe() Kamal Mostafa <kamal@canonical.com> - 2016-02-10 23:00 +0100
  [PATCH 3.13.y-ckt 08/30] iio: adis_buffer: Fix out-of-bounds memory access Kamal Mostafa <kamal@canonical.com> - 2016-02-10 23:00 +0100
  [PATCH 3.13.y-ckt 03/30] [media] usbvision: fix crash on detecting device with invalid configuration Kamal Mostafa <kamal@canonical.com> - 2016-02-10 23:00 +0100

csiph-web