From: Takashi Iwai Date: Thu, 28 Jan 2016 06:54:16 +0000 (+0100) Subject: ALSA: dummy: Disable switching timer backend via sysfs X-Git-Tag: v3.2.78~42 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=426c3ec8cb2d9dff76dbc34c3b19c4e681ac554e;hp=91edbdd78ad9ea458b9777353155a2b6c5746346 ALSA: dummy: Disable switching timer backend via sysfs 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 Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c index 97f1f93ed275..ebe9a83274ce 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