ALSA: hda: Abort capability probe at invalid register read
The loop in snd_hdac_bus_parse_capabilities() may go to nirvana when
it hits an invalid register value read:
BUG: unable to handle kernel paging request at ffffad5dc41f3fff
IP: pci_azx_readl+0x5/0x10 [snd_hda_intel]
Call Trace:
snd_hdac_bus_parse_capabilities+0x3c/0x1f0 [snd_hda_core]
azx_probe_continue+0x7d5/0x940 [snd_hda_intel]
.....
This happened on a new Intel machine, and we need to check the value
and abort the loop accordingly.
[Note: the fixes tag below indicates only the commit where this patch
can be applied; the original problem was introduced even before that
commit]
Fixes: 6720b38420a0 ("ALSA: hda - move bus_parse_capabilities to core")
Cc: <stable@vger.kernel.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/hda/hdac_controller.c b/sound/hda/hdac_controller.c
index 978dc18..f6d2985 100644
--- a/sound/hda/hdac_controller.c
+++ b/sound/hda/hdac_controller.c
@@ -284,6 +284,11 @@
dev_dbg(bus->dev, "HDA capability ID: 0x%x\n",
(cur_cap & AZX_CAP_HDR_ID_MASK) >> AZX_CAP_HDR_ID_OFF);
+ if (cur_cap == -1) {
+ dev_dbg(bus->dev, "Invalid capability reg read\n");
+ break;
+ }
+
switch ((cur_cap & AZX_CAP_HDR_ID_MASK) >> AZX_CAP_HDR_ID_OFF) {
case AZX_ML_CAP_ID:
dev_dbg(bus->dev, "Found ML capability\n");