linux-kernel - [PATCH 4.9 091/102] ALSA: usb-audio: fix sign unintended sign extension on left shifts

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Message-Id: <20190708150531.179422241@linuxfoundation.org>
Date:   Mon,  8 Jul 2019 17:13:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Ian King <colin.king@...onical.com>,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.9 091/102] ALSA: usb-audio: fix sign unintended sign extension on left shifts

From: Colin Ian King <colin.king@...onical.com>

commit 2acf5a3e6e9371e63c9e4ff54d84d08f630467a0 upstream.

There are a couple of left shifts of unsigned 8 bit values that
first get promoted to signed ints and hence get sign extended
on the shift if the top bit of the 8 bit values are set. Fix
this by casting the 8 bit values to unsigned ints to stop the
unintentional sign extension.

Addresses-Coverity: ("Unintended sign extension")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/usb/mixer_quirks.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -753,7 +753,7 @@ static int snd_ni_control_init_val(struc
 		return err;
 	}
 
-	kctl->private_value |= (value << 24);
+	kctl->private_value |= ((unsigned int)value << 24);
 	return 0;
 }
 
@@ -914,7 +914,7 @@ static int snd_ftu_eff_switch_init(struc
 	if (err < 0)
 		return err;
 
-	kctl->private_value |= value[0] << 24;
+	kctl->private_value |= (unsigned int)value[0] << 24;
 	return 0;
 }