ALSA: ac97: Fix incorrect bit shift at AC97-SPSA control write

Browse source

commit 7194eda1ba upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

This commit is contained in:

Takashi Iwai 2018-11-23 15:44:00 +01:00 • committed by Ben Hutchings

parent bc78b2c955

commit a4cd58f664

1 changed files with 1 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

2

sound/pci/ac97/ac97_codec.c

View file