ALSA: pcm: oss: Fix race at SNDCTL_DSP_SYNC

stable inclusion
from stable-v5.4.215
commit 4051324a6dafd7053c74c475e80b3ba10ae672b0
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5T9C3
CVE: CVE-2022-3303

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs?h=v6.0-rc5&id=8423f0b6d513b259fdab9c9bf4aaa6188d054c2d

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

[ Upstream commit 8423f0b6 ]

There is a small race window at snd_pcm_oss_sync() that is called from
OSS PCM SNDCTL_DSP_SYNC ioctl; namely the function calls
snd_pcm_oss_make_ready() at first, then takes the params_lock mutex
for the rest.  When the stream is set up again by another thread
between them, it leads to inconsistency, and may result in unexpected
results such as NULL dereference of OSS buffer as a fuzzer spotted
recently.

The fix is simply to cover snd_pcm_oss_make_ready() call into the same
params_lock mutex with snd_pcm_oss_make_ready_locked() variant.
Reported-and-tested-by: Nbutt3rflyh4ck <butterflyhuangxx@gmail.com>
Reviewed-by: NJaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/CAFcO6XN7JDM4xSXGhtusQfS2mSBcx50VJKwQpCq=WeLt57aaZA@mail.gmail.com
Link: https://lore.kernel.org/r/20220905060714.22549-1-tiwai@suse.deSigned-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NXia Longlong <xialonglong1@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

sound/core/oss/pcm_oss.c

@@ -1662,13 +1662,14 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
 		runtime = substream->runtime;
 		if (atomic_read(&substream->mmap_count))
 			goto __direct;
-		if ((err = snd_pcm_oss_make_ready(substream)) < 0)
-			return err;
 		atomic_inc(&runtime->oss.rw_ref);
 		if (mutex_lock_interruptible(&runtime->oss.params_lock)) {
 			atomic_dec(&runtime->oss.rw_ref);
 			return -ERESTARTSYS;
 		}
+		err = snd_pcm_oss_make_ready_locked(substream);
+		if (err < 0)
+			goto unlock;
 		format = snd_pcm_oss_format_from(runtime->oss.format);
 		width = snd_pcm_format_physical_width(format);
 		if (runtime->oss.buffer_used > 0) {