[PATCH 068/115] ALSA: HDA: Fix Oops caused by dereference NULL pointer

From: Luis Henriques
Date: Mon May 20 2013 - 06:53:37 EST -stable review patch. If anyone has any objections, please let me know.


From: Wang YanQing <udknight@xxxxxxxxx>

commit 2195b063f6609e4c6268f291683902f25eaf9aa6 upstream.

The interrupt handler azx_interrupt will call azx_update_rirb,
which may call snd_hda_queue_unsol_event, snd_hda_queue_unsol_event
will dereference chip->bus pointer.

The problem is we alloc chip->bus in azx_codec_create
which will be called after we enable IRQ and enable unsolicited
event in azx_probe.

This will cause Oops due dereference NULL pointer. I meet it, good luck:)

[Rearranged the NULL check before the tracepoint and added another
NULL check of bus->workq -- tiwai]

Signed-off-by: Wang YanQing <udknight@xxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
sound/pci/hda/hda_codec.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index e6b34c8..f33bb78 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -609,6 +609,9 @@ int snd_hda_queue_unsol_event(struct hda_bus *bus, u32 res, u32 res_ex)
struct hda_bus_unsolicited *unsol;
unsigned int wp;

+ if (!bus || !bus->workq)
+ return 0;
trace_hda_unsol_event(bus, res, res_ex);
unsol = bus->unsol;
if (!unsol)

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