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authorTakashi Iwai <tiwai@suse.de>2020-12-09 09:45:52 +0100
committerTakashi Iwai <tiwai@suse.de>2020-12-14 09:10:39 +0100
commit175b8d89fe292796811fdee87fa39799a5b6b87a (patch)
tree2188693002fdf3c7e765d78be8a83b8c289f35c4 /sound/core/oss/pcm_oss.c
parent43d5ca88dfcd35e43010fdd818e067aa9a55f5ba (diff)
ALSA: pcm: oss: Fix potential out-of-bounds shift
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> Link: https://lore.kernel.org/r/20201209084552.17109-2-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core/oss/pcm_oss.c')
-rw-r--r--sound/core/oss/pcm_oss.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 327ec42a36b0..de1917484647 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -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;