@@ -1935,11 +1935,15 @@ static int snd_pcm_oss_set_subdivide(struct snd_pcm_oss_file *pcm_oss_file, int
static int snd_pcm_oss_set_fragment1(struct snd_pcm_substream *substream, unsigned int val)
{
struct snd_pcm_runtime *runtime;
+ int fragshift;
runtime = substream->runtime;
if (runtime->oss.subdivision || runtime->oss.fragshift)
return -EINVAL;
- runtime->oss.fragshift = val & 0xffff;
+ fragshift = val & 0xffff;
+ if (fragshift >= 31)
+ return -EINVAL;
+ runtime->oss.fragshift = fragshift;
runtime->oss.maxfrags = (val >> 16) & 0xffff;
if (runtime->oss.fragshift < 4) /* < 16 */
runtime->oss.fragshift = 4;
syzbot spotted a potential out-of-bounds shift in the PCM OSS layer where it calculates the buffer size with the arbitrary shift value given via an ioctl. Add a range check for avoiding the undefined behavior. As the value can be treated by a signed integer, the max shift should be 30. Reported-by: syzbot+df7dc146ebdd6435eea3@syzkaller.appspotmail.com Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> --- sound/core/oss/pcm_oss.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)