From d8bbf63f906acb9e98a8d61265bfd22bbdb159b1 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 28 Jan 2016 07:54:16 +0100 Subject: [PATCH] ALSA: dummy: Disable switching timer backend via sysfs Orabug: 23330790 [ Upstream commit 7ee96216c31aabe1eb42fb91ff50dae9fcd014b2 ] 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 Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin (cherry picked from commit f6b4419806e546fb02f91bed03572362e2623879) Signed-off-by: Dan Duval --- 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 d11baaf0f0b4..96592d5ba7bf 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 -- 2.50.1