linux-kernel - [PATCH 1/2] interconnect: Add character pointer initialization

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Message-ID: <20240830102244.409058-1-Yibin.Ding@unisoc.com>
Date: Fri, 30 Aug 2024 18:22:44 +0800
From: Yibin Ding <Yibin.Ding@...soc.com>
To: <djakov@...nel.org>, <gregkh@...uxfoundation.org>, <rafael@...nel.org>
CC: <yibin.ding01@...il.com>, <niuzhiguo84@...il.com>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <Hao_hao.Wang@...soc.com>, <Ke.Wang@...soc.com>
Subject: [PATCH 1/2] interconnect: Add character pointer initialization

From: Yibin Ding <Yibin.ding@...soc.com>

When accessing a node whose data type is a character pointer and has not
been initialized, a crash will occur due to accessing a null pointer. So
it is necessary to add the operation of initializing the character pointer.
Since the debugfs_write_file_str() function performs a kfree() operation
on the node data, memory is allocated to the node pointer during
initialization will be released when data is written to the node.

Signed-off-by: Yibin Ding <Yibin.ding@...soc.com>
---
 drivers/interconnect/debugfs-client.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/interconnect/debugfs-client.c b/drivers/interconnect/debugfs-client.c
index bc3fd8a7b9eb..d62ba56b7bbe 100644
--- a/drivers/interconnect/debugfs-client.c
+++ b/drivers/interconnect/debugfs-client.c
@@ -16,6 +16,7 @@
 #undef INTERCONNECT_ALLOW_WRITE_DEBUGFS
 
 #if defined(INTERCONNECT_ALLOW_WRITE_DEBUGFS) && defined(CONFIG_DEBUG_FS)
+#define INITNODE_SIZE 1
 
 static LIST_HEAD(debugfs_paths);
 static DEFINE_MUTEX(debugfs_lock);
@@ -147,8 +148,13 @@ int icc_debugfs_client_init(struct dentry *icc_dir)
 
 	client_dir = debugfs_create_dir("test_client", icc_dir);
 
-	debugfs_create_str("src_node", 0600, client_dir, &src_node);
-	debugfs_create_str("dst_node", 0600, client_dir, &dst_node);
+	src_node = kzalloc(INITNODE_SIZE, GFP_KERNEL);
+	dst_node = kzalloc(INITNODE_SIZE, GFP_KERNEL);
+
+	if (src_node)
+		debugfs_create_str("src_node", 0600, client_dir, &src_node);
+	if (dst_node)
+		debugfs_create_str("dst_node", 0600, client_dir, &dst_node);
 	debugfs_create_file("get", 0200, client_dir, NULL, &icc_get_fops);
 	debugfs_create_u32("avg_bw", 0600, client_dir, &avg_bw);
 	debugfs_create_u32("peak_bw", 0600, client_dir, &peak_bw);
-- 
2.25.1