[PATCH 5.10 37/86] ALSA: usb-audio: Fix undefined behavior due to shift overflowing the constant

Greg Kroah-Hartman
2022-04-26T09:17:21Z

From: Borislav Petkov <bp@suse.de>

[ Upstream commit 1ef8715975de8bd481abbd0839ed4f49d9e5b0ff ]

Fix:

sound/usb/midi.c: In function ‘snd_usbmidi_out_endpoint_create’:
sound/usb/midi.c:1389:2: error: case label does not reduce to an integer constant
case USB_ID(0xfc08, 0x0101): /* Unknown vendor Cable */
^~~~

See https://lore.kernel.org/r/YkwQ6%2BtIH8GQpuct@zn.tnic for the gory
details as to why it triggers with older gccs only.

[ A slight correction with parentheses around the argument by tiwai ]

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220405151517.29753-3-bp@alien8.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/usb/usbaudio.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index e54a98f46549..d8e31ee03b9d 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -8,7 +8,7 @@
*/

/* handling of USB vendor/product ID pairs as 32-bit numbers */
-#define USB_ID(vendor, product) (((vendor) << 16) | (product))
+#define USB_ID(vendor, product) (((unsigned int)(vendor) << 16) | (product))
#define USB_ID_VENDOR(id) ((id) >> 16)
#define USB_ID_PRODUCT(id) ((u16)(id))

--
2.35.1