提交 b99591ce 编写于 作者: T Takashi Iwai 提交者: Chen Jun

ALSA: pcm: oss: Fix potential out-of-bounds shift

stable inclusion
from stable-5.10.2
commit ff654f1d31d5fe2962ea49476635c795653e289a
bugzilla: 46859

--------------------------------

commit 175b8d89 upstream.

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.deSigned-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
上级 3b74a81e
......@@ -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;
......
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