[PATCH HID 1/3] HID: uclogic: Correct devm device reference for hidinput input_dev name

[Rahul Rameshbabu <sergeantsagara@protonmail.com>]

Reference the HID device rather than the input device for the devm
allocation of the input_dev name. Referencing the input_dev would lead to a
use-after-free when the input_dev was unregistered and subsequently fires a
uevent that depends on the name. At the point of firing the uevent, the
name would be freed by devres management.

Use devm_kasprintf to simplify the logic for allocating memory and
formatting the input_dev name string.

Reported-by: syzbot+3a0ebe8a52b89c63739d@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-input/ZOZIZCND+L0P1wJc@penguin/T/
Reported-by: Maxime Ripard <mripard@kernel.org>
Closes: https://lore.kernel.org/linux-input/ZOZIZCND+L0P1wJc@penguin/T/#m443f3dce92520f74b6cf6ffa8653f9c92643d4ae
Fixes: cce2dbdf258e ("HID: uclogic: name the input nodes based on their tool")
Suggested-by: Maxime Ripard <mripard@kernel.org>
Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
---
 drivers/hid/hid-uclogic-core.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/hid/hid-uclogic-core.c b/drivers/hid/hid-uclogic-core.c
index f67835f9ed4c..ad74cbc9a0aa 100644
--- a/drivers/hid/hid-uclogic-core.c
+++ b/drivers/hid/hid-uclogic-core.c
@@ -85,10 +85,8 @@ static int uclogic_input_configured(struct hid_device *hdev,
 {
 	struct uclogic_drvdata *drvdata = hid_get_drvdata(hdev);
 	struct uclogic_params *params = &drvdata->params;
-	char *name;
 	const char *suffix = NULL;
 	struct hid_field *field;
-	size_t len;
 	size_t i;
 	const struct uclogic_params_frame *frame;
 
@@ -146,14 +144,9 @@ static int uclogic_input_configured(struct hid_device *hdev,
 		}
 	}
 
-	if (suffix) {
-		len = strlen(hdev->name) + 2 + strlen(suffix);
-		name = devm_kzalloc(&hi->input->dev, len, GFP_KERNEL);
-		if (name) {
-			snprintf(name, len, "%s %s", hdev->name, suffix);
-			hi->input->name = name;
-		}
-	}
+	if (suffix)
+		hi->input->name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+						 "%s %s", hdev->name, suffix);
 
 	return 0;
 }
-- 
2.40.1