From:   Jiasheng Jiang <jiasheng@iscas.ac.cn>
To:     elder@ieee.org, vaibhav.sr@gmail.com, mgreer@animalcreek.com,
        johan@kernel.org, elder@kernel.org, gregkh@linuxfoundation.org
Cc:     greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev,
        linux-kernel@vger.kernel.org, Jiasheng Jiang <jiasheng@iscas.ac.cn>
Subject: [PATCH v3] staging: greybus: audio: Check null pointer
Date:   Tue,  4 Jan 2022 23:06:28 +0800
Message-Id: <20220104150628.1987906-1-jiasheng@iscas.ac.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

As the possible alloc failure of devm_kcalloc(), it could return null
pointer.
Therefore, 'strings' should be checked and return NULL if alloc fails to
prevent the dereference of the NULL pointer.
Also, the caller should also deal with the return value of the
gb_generate_enum_strings() and return -ENOMEM if returns NULL.
Moreover, because the memory allocated with devm_kzalloc() will be
freed automatically when the last reference to the device is dropped,
the 'gbe' in gbaudio_tplg_create_enum_kctl() and
gbaudio_tplg_create_enum_ctl() do not need to free manually.
But the 'control' in gbaudio_tplg_create_widget() and
gbaudio_tplg_process_kcontrols() has a specially error handle to
cleanup.
So it should be better to cleanup 'control' when fails.

Fixes: e65579e335da ("greybus: audio: topology: Enable enumerated control support")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
v3: Same code as v2, but remove the redundant message as requested.
v2: Updated to use common error processing at the end of both
gbaudio_tplg_create_widget() and gbaudio_tplg_process_kcontrols().
---
 drivers/staging/greybus/audio_topology.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/staging/greybus/audio_topology.c b/drivers/staging/greybus/audio_topology.c
index 1fc7727ab7be..6bba735d2e5c 100644
--- a/drivers/staging/greybus/audio_topology.c
+++ b/drivers/staging/greybus/audio_topology.c
@@ -147,6 +147,9 @@ static const char **gb_generate_enum_strings(struct gbaudio_module_info *gb,
 
 	items = le32_to_cpu(gbenum->items);
 	strings = devm_kcalloc(gb->dev, items, sizeof(char *), GFP_KERNEL);
+	if (!strings)
+		return NULL;
+
 	data = gbenum->names;
 
 	for (i = 0; i < items; i++) {
@@ -655,6 +658,8 @@ static int gbaudio_tplg_create_enum_kctl(struct gbaudio_module_info *gb,
 	/* since count=1, and reg is dummy */
 	gbe->items = le32_to_cpu(gb_enum->items);
 	gbe->texts = gb_generate_enum_strings(gb, gb_enum);
+	if (!gbe->texts)
+		return -ENOMEM;
 
 	/* debug enum info */
 	dev_dbg(gb->dev, "Max:%d, name_length:%d\n", gbe->items,
@@ -862,6 +867,8 @@ static int gbaudio_tplg_create_enum_ctl(struct gbaudio_module_info *gb,
 	/* since count=1, and reg is dummy */
 	gbe->items = le32_to_cpu(gb_enum->items);
 	gbe->texts = gb_generate_enum_strings(gb, gb_enum);
+	if (!gbe->texts)
+		return -ENOMEM;
 
 	/* debug enum info */
 	dev_dbg(gb->dev, "Max:%d, name_length:%d\n", gbe->items,
@@ -1034,6 +1041,10 @@ static int gbaudio_tplg_create_widget(struct gbaudio_module_info *module,
 			csize += le16_to_cpu(gbenum->names_length);
 			control->texts = (const char * const *)
 				gb_generate_enum_strings(module, gbenum);
+			if (!control->texts) {
+				ret = -ENOMEM;
+				goto error;
+			}
 			control->items = le32_to_cpu(gbenum->items);
 		} else {
 			csize = sizeof(struct gb_audio_control);
@@ -1183,6 +1194,10 @@ static int gbaudio_tplg_process_kcontrols(struct gbaudio_module_info *module,
 			csize += le16_to_cpu(gbenum->names_length);
 			control->texts = (const char * const *)
 				gb_generate_enum_strings(module, gbenum);
+			if (!control->texts) {
+				ret = -ENOMEM;
+				goto error;
+			}
 			control->items = le32_to_cpu(gbenum->items);
 		} else {
 			csize = sizeof(struct gb_audio_control);
-- 
2.25.1