path: root/sound
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authorTakashi Iwai <tiwai@suse.de>2018-11-23 15:44:00 +0100
committerTakashi Iwai <tiwai@suse.de>2018-11-23 18:09:22 +0100
commit7194eda1ba0872d917faf3b322540b4f57f11ba5 (patch)
treebf7b0ad9b193f4766c0a979c4a298076548d0281 /sound
parenta6b0961b39896a9f9f1350d26d202f078a7d9dbc (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')
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;