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authorTakashi Iwai <tiwai@suse.de>2020-05-16 08:25:56 +0200
committerTakashi Iwai <tiwai@suse.de>2020-05-16 08:27:11 +0200
commitc637fa151259c0f74665fde7cba5b7eac1417ae5 (patch)
tree21ad2119571d846a01fa103eb8505e447210cdab
parent10ce77e4817fef99e1166be7e6685a80c63bf77f (diff)
ALSA: hda: Fix potential race in unsol event handler
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>
-rw-r--r--sound/hda/hdac_bus.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/hda/hdac_bus.c b/sound/hda/hdac_bus.c
index 3fe62be1cbcc..dee04792ca86 100644
--- a/sound/hda/hdac_bus.c
+++ b/sound/hda/hdac_bus.c
@@ -162,6 +162,7 @@ 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;
@@ -173,10 +174,13 @@ 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);
}
/**