[PATCH] ALSA: usb-audio: Fix regression on detection of Roland VS-100

[PATCH] ALSA: usb-audio: Fix regression on detection of Roland VS-100

[Takashi Iwai]

It's been reported that the recent kernel can't probe the PCM devices
on Roland VS-100 properly, and it turned out to be a regression by the
recent addition of the bit shift range check for the format bits.
In the old code, we just did bit-shift and it resulted in zero, which
is then corrected to the standard PCM format, while the new code
explicitly returns an error in such a case.

For addressing the regression, relax the check and fallback to the
standard PCM type (with the info output).

Fixes: 43d5ca88dfcd ("ALSA: usb-audio: Fix potential out-of-bounds shift")
Cc: <stable@vger.kernel.org>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217084
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/usb/format.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sound/usb/format.c b/sound/usb/format.c
index 405dc0bf6678..4b1c5ba121f3 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -39,8 +39,12 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
 	case UAC_VERSION_1:
 	default: {
 		struct uac_format_type_i_discrete_descriptor *fmt = _fmt;
-		if (format >= 64)
-			return 0; /* invalid format */
+		if (format >= 64) {
+			usb_audio_info(chip,
+				       "%u:%d: invalid format type 0x%llx is detected, processed as PCM\n",
+				       fp->iface, fp->altsetting, format);
+			format = UAC_FORMAT_TYPE_I_PCM;
+		}
 		sample_width = fmt->bBitResolution;
 		sample_bytes = fmt->bSubframeSize;
 		format = 1ULL << format;
-- 
2.35.3