diff options
| author | Takashi Iwai <tiwai@suse.de> | 2018-11-23 15:44:00 +0100 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2018-11-23 18:09:22 +0100 |
| commit | 7194eda1ba0872d917faf3b322540b4f57f11ba5 (patch) | |
| tree | bf7b0ad9b193f4766c0a979c4a298076548d0281 /sound | |
| parent | a6b0961b39896a9f9f1350d26d202f078a7d9dbc (diff) | |
ALSA: ac97: Fix incorrect bit shift at AC97-SPSA control write
The function snd_ac97_put_spsa() gets the bit shift value from the
associated private_value, but it extracts too much; the current code
extracts 8 bit values in bits 8-15, but this is a combination of two
nibbles (bits 8-11 and bits 12-15) for left and right shifts.
Due to the incorrect bits extraction, the actual shift may go beyond
the 32bit value, as spotted recently by UBSAN check:
UBSAN: Undefined behaviour in sound/pci/ac97/ac97_codec.c:836:7
shift exponent 68 is too large for 32-bit type 'int'
This patch fixes the shift value extraction by masking the properly
with 0x0f instead of 0xff.
Reported-and-tested-by: Meelis Roos <mroos@linux.ee>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/pci/ac97/ac97_codec.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/pci/ac97/ac97_codec.c b/sound/pci/ac97/ac97_codec.c index f4459d1a9d67..27b468f057dd 100644 --- a/sound/pci/ac97/ac97_codec.c +++ b/sound/pci/ac97/ac97_codec.c @@ -824,7 +824,7 @@ static int snd_ac97_put_spsa(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_ { struct snd_ac97 *ac97 = snd_kcontrol_chip(kcontrol); int reg = kcontrol->private_value & 0xff; - int shift = (kcontrol->private_value >> 8) & 0xff; + int shift = (kcontrol->private_value >> 8) & 0x0f; int mask = (kcontrol->private_value >> 16) & 0xff; // int invert = (kcontrol->private_value >> 24) & 0xff; unsigned short value, old, new; |