From: Takashi Iwai Date: Thu, 28 Jan 2016 06:54:16 +0000 (+0100) Subject: ALSA: dummy: Disable switching timer backend via sysfs X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=7ee96216c31aabe1eb42fb91ff50dae9fcd014b2;p=openwrt%2Fstaging%2Fblogic.git ALSA: dummy: Disable switching timer backend via sysfs 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 --- diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c index 75b74850c005..bde33308f0d6 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