From: Takashi Iwai tiwai@suse.de
stable inclusion from stable-v4.19.221 commit 2e54cf6794bf82a54aaefc78da13819aea9cd28a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9S1ZV CVE: CVE-2021-47509
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 8839c8c0f77ab8fc0463f4ab8b37fca3f70677c2 upstream.
Set the practical limit to the period size (the fragment shift in OSS) instead of a full 31bit; a too large value could lead to the exhaust of memory as we allocate temporary buffers of the period size, too.
As of this patch, we set to 16MB limit, which should cover all use cases.
Reported-by: syzbot+bb348e9f9a954d42746f@syzkaller.appspotmail.com Reported-by: Bixuan Cui cuibixuan@linux.alibaba.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/1638270978-42412-1-git-send-email-cuibixuan@linux.... Link: https://lore.kernel.org/r/20211201073606.11660-3-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- sound/core/oss/pcm_oss.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c index 6baf50f4def3..7f434a37d860 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -1968,7 +1968,7 @@ static int snd_pcm_oss_set_fragment1(struct snd_pcm_substream *substream, unsign if (runtime->oss.subdivision || runtime->oss.fragshift) return -EINVAL; fragshift = val & 0xffff; - if (fragshift >= 31) + if (fragshift >= 25) /* should be large enough */ return -EINVAL; runtime->oss.fragshift = fragshift; runtime->oss.maxfrags = (val >> 16) & 0xffff;