[PATCH 6.1.y 1/2] ASoC: SOF: avoid a NULL dereference with unsupported widgets

[Artem Dinaburg <artem@trailofbits.com>]

From: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

[ Upstream commit e3720f92e0237921da537e47a0b24e27899203f8 ]

If an IPC4 topology contains an unsupported widget, its .module_info
field won't be set, then sof_ipc4_route_setup() will cause a kernel
Oops trying to dereference it. Add a check for such cases.

Cc: stable@vger.kernel.org # 6.2
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230329113828.28562-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

[ Backport to 6.1.y: although the upstream stable tag names 6.2, the
  same module_info dereference is present here; the source change is
  otherwise unchanged. ]
Assisted-by: LLM
Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
---
Stable submission note: patch 1/2 in the CVE-2023-54233 series for Linux
6.1.y.

CVE: CVE-2023-54233

Build: This patch was included in the x86_64 allmodconfig and
CONFIG_WERROR=y build.
It produced vmlinux and 9,075 modules; the same four baseline objtool
notices appeared, with no new warnings or errors.

 sound/soc/sof/ipc4-topology.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/soc/sof/ipc4-topology.c b/sound/soc/sof/ipc4-topology.c
index 49289932ba7e69..9540ba6ef659e6 100644
--- a/sound/soc/sof/ipc4-topology.c
+++ b/sound/soc/sof/ipc4-topology.c
@@ -1600,6 +1600,14 @@ static int sof_ipc4_route_setup(struct snd_sof_dev *sdev, struct snd_sof_route *
 	int dst_queue = 0;
 	int ret;
 
+	if (!src_fw_module || !sink_fw_module) {
+		/* The NULL module will print as "(efault)" */
+		dev_err(sdev->dev, "source %s or sink %s widget weren't set up properly\n",
+			src_fw_module->man4_module_entry.name,
+			sink_fw_module->man4_module_entry.name);
+		return -ENODEV;
+	}
+
 	dev_dbg(sdev->dev, "bind %s -> %s\n",
 		src_widget->widget->name, sink_widget->widget->name);
 
-- 
2.39.5