linux-kernel - [PATCH AUTOSEL 4.14 7/9] ALSA: hda: Fix possible null-ptr-deref when assigning a stream

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Message-ID: <20231107155509.3769038-7-sashal@kernel.org>
Date:   Tue,  7 Nov 2023 10:54:57 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Cezary Rojewski <cezary.rojewski@...el.com>,
        Takashi Iwai <tiwai@...e.de>, Sasha Levin <sashal@...nel.org>,
        perex@...ex.cz, tiwai@...e.com, broonie@...nel.org,
        pierre-louis.bossart@...ux.intel.com, mengyingkun@...ngson.cn,
        zhangyiqun@...tium.com.cn, siyanteng@...ngson.cn,
        linux-sound@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 7/9] ALSA: hda: Fix possible null-ptr-deref when assigning a stream

From: Cezary Rojewski <cezary.rojewski@...el.com>

[ Upstream commit f93dc90c2e8ed664985e366aa6459ac83cdab236 ]

While AudioDSP drivers assign streams exclusively of HOST or LINK type,
nothing blocks a user to attempt to assign a COUPLED stream. As
supplied substream instance may be a stub, what is the case when
code-loading, such scenario ends with null-ptr-deref.

Signed-off-by: Cezary Rojewski <cezary.rojewski@...el.com>
Link: https://lore.kernel.org/r/20231006102857.749143-2-cezary.rojewski@intel.com
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/hda/hdac_stream.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
index e1472c7ab6c17..609dc5133fba9 100644
--- a/sound/hda/hdac_stream.c
+++ b/sound/hda/hdac_stream.c
@@ -241,8 +241,10 @@ struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
 	struct hdac_stream *res = NULL;
 
 	/* make a non-zero unique key for the substream */
-	int key = (substream->pcm->device << 16) | (substream->number << 2) |
-		(substream->stream + 1);
+	int key = (substream->number << 2) | (substream->stream + 1);
+
+	if (substream->pcm)
+		key |= (substream->pcm->device << 16);
 
 	list_for_each_entry(azx_dev, &bus->stream_list, list) {
 		if (azx_dev->direction != substream->stream)
-- 
2.42.0