linux-kernel - [PATCH v2] HID: uclogic: Add NULL check in uclogic_input

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Message-Id: <20250401063157.19655-1-bsdhenrymartin@gmail.com>
Date: Tue,  1 Apr 2025 14:31:57 +0800
From: Henry Martin <bsdhenrymartin@...il.com>
To: jikos@...nel.org,
	bentiss@...nel.org
Cc: linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Henry Martin <bsdhenrymartin@...il.com>
Subject: [PATCH v2] HID: uclogic: Add NULL check in uclogic_input_configured

devm_kasprintf() returns NULL when memory allocation fails. Currently,
uclogic_input_configured() does not check for this case, which results in a
NULL pointer dereference.

Add NULL check after devm_kasprintf() to prevent this issue.

Fixes: dd613a4e45f8 ("HID: uclogic: Correct devm device reference for hidinput input_dev name")
Signed-off-by: Henry Martin <bsdhenrymartin@...il.com>
---
V1 -> V2: 
Simplify the handing of the condition "suffix" with if/else suggested by
Markus. 
The current implementation (directly returning -ENOMEM) is reasonable because:
1. pen_input is just a cached pointer - no resources are allocated
2. evbit modification is a software-only configuration (hardware-independent)
3. No critical state needs rollback on memory allocation failure

 drivers/hid/hid-uclogic-core.c | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/drivers/hid/hid-uclogic-core.c b/drivers/hid/hid-uclogic-core.c
index d8008933c052..83625ec6a55a 100644
--- a/drivers/hid/hid-uclogic-core.c
+++ b/drivers/hid/hid-uclogic-core.c
@@ -118,35 +118,29 @@ static int uclogic_input_configured(struct hid_device *hdev,
 		}
 	}
 
-	if (!suffix) {
+	if (!suffix && hi->report->maxfield > 0) {
 		field = hi->report->field[0];
 
-		switch (field->application) {
-		case HID_GD_KEYBOARD:
+		if (field->application == HID_GD_KEYBOARD)
 			suffix = "Keyboard";
-			break;
-		case HID_GD_MOUSE:
+		else if (field->application == HID_GD_MOUSE)
 			suffix = "Mouse";
-			break;
-		case HID_GD_KEYPAD:
+		else if (field->application == HID_GD_KEYPAD)
 			suffix = "Pad";
-			break;
-		case HID_DG_PEN:
-		case HID_DG_DIGITIZER:
+		else if (field->application == HID_DG_PEN || field->application == HID_DG_DIGITIZER)
 			suffix = "Pen";
-			break;
-		case HID_CP_CONSUMER_CONTROL:
+		else if (field->application == HID_CP_CONSUMER_CONTROL)
 			suffix = "Consumer Control";
-			break;
-		case HID_GD_SYSTEM_CONTROL:
+		else if (field->application == HID_GD_SYSTEM_CONTROL)
 			suffix = "System Control";
-			break;
-		}
 	}
 
-	if (suffix)
+	if (suffix) {
 		hi->input->name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
 						 "%s %s", hdev->name, suffix);
+		if (!hi->input->name)
+			return -ENOMEM;
+	}
 
 	return 0;
 }
-- 
2.34.1