HID: uclogic: Correct devm device reference for hidinput input_dev name

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>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20230824061308.222021-2-sergeantsagara@protonmail.com
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

diff --git a/drivers/hid/hid-uclogic-core.c b/drivers/hid/hid-uclogic-core.c
index f67835f9ed4ccae359271e401a3e40f2fd282b00..ad74cbc9a0aa59f24e55acb7f935bbae442f93ee 100644 (file)
--- 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;
 }