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ALSA: hda: Fix potential race in unsol event handler 

[ Upstream commit c637fa1512 ]

The unsol event handling code has a loop retrieving the read/write
indices and the arrays without locking while the append to the array
may happen concurrently.  This may lead to some inconsistency.
Although there hasn't been any proof of this bad results, it's still
safer to protect the racy accesses.

This patch adds the spinlock protection around the unsol handling loop
for addressing it.  Here we take bus->reg_lock as the writer side
snd_hdac_bus_queue_event() is also protected by that lock.

Link: https://lore.kernel.org/r/20200516062556.30951-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Takashi Iwai 2020-05-16 08:25:56 +02:00 committed by Greg Kroah-Hartman
parent 942a6ff214
commit 7ce7dd0a6f
1 changed files with 4 additions and 0 deletions
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4
sound/hda/hdac_bus.c
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@ -158,6 +158,7 @@ static void snd_hdac_bus_process_unsol_events(struct work_struct *work)
struct hdac_driver *drv;
unsigned int rp, caddr, res;
spin_lock_irq(&bus->reg_lock);
while (bus->unsol_rp != bus->unsol_wp) {
rp = (bus->unsol_rp + 1) % HDA_UNSOL_QUEUE_SIZE;
bus->unsol_rp = rp;
@ -169,10 +170,13 @@ static void snd_hdac_bus_process_unsol_events(struct work_struct *work)
codec = bus->caddr_tbl[caddr & 0x0f];
if (!codec || !codec->dev.driver)
continue;
spin_unlock_irq(&bus->reg_lock);
drv = drv_to_hdac_driver(codec->dev.driver);
if (drv->unsol_event)
drv->unsol_event(codec, res);
spin_lock_irq(&bus->reg_lock);
}
spin_unlock_irq(&bus->reg_lock);
}
/**