sound: usb-audio: fix rules check for 32-channel devices

When storing the channel numbers used by a format, and if the device
happens to support 32 channels, the code would try to store 1<<32 in
a 32-bit value.

Since no valid format can have zero channels, we can use 1<<(channels-1)
instead of 1<<channels so that all the channel numbers that we test for
fit into 32 bits.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 2b24496ddec7..f853b627cf43 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -1783,7 +1783,7 @@ static int check_hw_params_convention(struct snd_usb_substream *subs)
                         if (rates[f->format] && rates[f->format] != f->rates)
                                 goto __out;
                 }
-                channels[f->format] |= (1 << f->channels);
+                channels[f->format] |= 1 << (f->channels - 1);
                 rates[f->format] |= f->rates;
                 /* needs knot? */
                 if (f->rates & SNDRV_PCM_RATE_KNOT)
@@ -1810,7 +1810,7 @@ static int check_hw_params_convention(struct snd_usb_substream *subs)
                         continue;
                 for (i = 0; i < 32; i++) {
                         if (f->rates & (1 << i))
-                                channels[i] |= (1 << f->channels);
+                                channels[i] |= 1 << (f->channels - 1);
                 }
         }
         cmaster = 0;