The logic in dualshock4_get_calibration_data() used uninitialised data
in case of a failed kzalloc() for the transfer buffer.

The solution is to group all business logic and all sanity checks
together, and jump only to the latter in case of an error.
While we're at it, factor out the axes' labelling, since it must happen
either way for input_report_abs() to succeed later on.

Thanks to Dan Carpenter for the Smatch static checker warning.

Fixes: a48a7cd85f55 ("HID: playstation: DS4: Don't fail on calibration data request")
Signed-off-by: Max Staudt <max@enpas.org>
---
Changes in v1 -> v2:
 - Restored assignments to .abs_code in their original location
 - Added assignments to .abs_code in the error handling loops
---
 drivers/hid/hid-playstation.c | 52 +++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 24 deletions(-)

diff --git a/drivers/hid/hid-playstation.c b/drivers/hid/hid-playstation.c
index edc46fc02e9a..e7c309cfe3a0 100644
--- a/drivers/hid/hid-playstation.c
+++ b/drivers/hid/hid-playstation.c
@@ -1787,7 +1787,7 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 		buf = kzalloc(DS4_FEATURE_REPORT_CALIBRATION_SIZE, GFP_KERNEL);
 		if (!buf) {
 			ret = -ENOMEM;
-			goto no_buffer_tail_check;
+			goto transfer_failed;
 		}
 
 		/* We should normally receive the feature report data we asked
@@ -1807,6 +1807,7 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 
 				hid_warn(hdev, "Failed to retrieve DualShock4 calibration info: %d\n", ret);
 				ret = -EILSEQ;
+				goto transfer_failed;
 			} else {
 				break;
 			}
@@ -1815,17 +1816,19 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 		buf = kzalloc(DS4_FEATURE_REPORT_CALIBRATION_BT_SIZE, GFP_KERNEL);
 		if (!buf) {
 			ret = -ENOMEM;
-			goto no_buffer_tail_check;
+			goto transfer_failed;
 		}
 
 		ret = ps_get_report(hdev, DS4_FEATURE_REPORT_CALIBRATION_BT, buf,
 				DS4_FEATURE_REPORT_CALIBRATION_BT_SIZE, true);
 
-		if (ret)
+		if (ret) {
 			hid_warn(hdev, "Failed to retrieve DualShock4 calibration info: %d\n", ret);
+			goto transfer_failed;
+		}
 	}
 
-	/* Parse buffer. If the transfer failed, this safely copies zeroes. */
+	/* Transfer succeeded - parse the calibration data received. */
 	gyro_pitch_bias  = get_unaligned_le16(&buf[1]);
 	gyro_yaw_bias    = get_unaligned_le16(&buf[3]);
 	gyro_roll_bias   = get_unaligned_le16(&buf[5]);
@@ -1854,6 +1857,9 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 	acc_z_plus       = get_unaligned_le16(&buf[31]);
 	acc_z_minus      = get_unaligned_le16(&buf[33]);
 
+	/* Done parsing the buffer, so let's free it. */
+	kfree(buf);
+
 	/*
 	 * Set gyroscope calibration and normalization parameters.
 	 * Data values will be normalized to 1/DS4_GYRO_RES_PER_DEG_S degree/s.
@@ -1877,26 +1883,6 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 	ds4->gyro_calib_data[2].sens_denom = abs(gyro_roll_plus - gyro_roll_bias) +
 			abs(gyro_roll_minus - gyro_roll_bias);
 
-	/* Done parsing the buffer, so let's free it. */
-	kfree(buf);
-
-no_buffer_tail_check:
-
-	/*
-	 * Sanity check gyro calibration data. This is needed to prevent crashes
-	 * during report handling of virtual, clone or broken devices not implementing
-	 * calibration data properly.
-	 */
-	for (i = 0; i < ARRAY_SIZE(ds4->gyro_calib_data); i++) {
-		if (ds4->gyro_calib_data[i].sens_denom == 0) {
-			hid_warn(hdev, "Invalid gyro calibration data for axis (%d), disabling calibration.",
-					ds4->gyro_calib_data[i].abs_code);
-			ds4->gyro_calib_data[i].bias = 0;
-			ds4->gyro_calib_data[i].sens_numer = DS4_GYRO_RANGE;
-			ds4->gyro_calib_data[i].sens_denom = S16_MAX;
-		}
-	}
-
 	/*
 	 * Set accelerometer calibration and normalization parameters.
 	 * Data values will be normalized to 1/DS4_ACC_RES_PER_G g.
@@ -1919,6 +1905,23 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 	ds4->accel_calib_data[2].sens_numer = 2*DS4_ACC_RES_PER_G;
 	ds4->accel_calib_data[2].sens_denom = range_2g;
 
+transfer_failed:
+	/*
+	 * Sanity check gyro calibration data. This is needed to prevent crashes
+	 * during report handling of virtual, clone or broken devices not implementing
+	 * calibration data properly.
+	 */
+	for (i = 0; i < ARRAY_SIZE(ds4->gyro_calib_data); i++) {
+		if (ds4->gyro_calib_data[i].sens_denom == 0) {
+			ds4->gyro_calib_data[i].abs_code = ABS_RX + i;
+			hid_warn(hdev, "Invalid gyro calibration data for axis (%d), disabling calibration.",
+					ds4->gyro_calib_data[i].abs_code);
+			ds4->gyro_calib_data[i].bias = 0;
+			ds4->gyro_calib_data[i].sens_numer = DS4_GYRO_RANGE;
+			ds4->gyro_calib_data[i].sens_denom = S16_MAX;
+		}
+	}
+
 	/*
 	 * Sanity check accelerometer calibration data. This is needed to prevent crashes
 	 * during report handling of virtual, clone or broken devices not implementing calibration
@@ -1926,6 +1929,7 @@ static int dualshock4_get_calibration_data(struct dualshock4 *ds4)
 	 */
 	for (i = 0; i < ARRAY_SIZE(ds4->accel_calib_data); i++) {
 		if (ds4->accel_calib_data[i].sens_denom == 0) {
+			ds4->accel_calib_data[i].abs_code = ABS_X + i;
 			hid_warn(hdev, "Invalid accelerometer calibration data for axis (%d), disabling calibration.",
 					ds4->accel_calib_data[i].abs_code);
 			ds4->accel_calib_data[i].bias = 0;
-- 
2.39.2

On Sun, 5 May 2024, Max Staudt wrote:

> The logic in dualshock4_get_calibration_data() used uninitialised data
> in case of a failed kzalloc() for the transfer buffer.

Good catch, this completely escaped my attention during review.

> 
> The solution is to group all business logic and all sanity checks
> together, and jump only to the latter in case of an error.
> While we're at it, factor out the axes' labelling, since it must happen
> either way for input_report_abs() to succeed later on.
> 
> Thanks to Dan Carpenter for the Smatch static checker warning.
> 
> Fixes: a48a7cd85f55 ("HID: playstation: DS4: Don't fail on calibration data request")
> Signed-off-by: Max Staudt <max@enpas.org>

Now queued on top of the for-6.10/playstation pile in hid.git.

Thanks,

-- 
Jiri Kosina
SUSE Labs

On 5/7/24 06:32, Jiri Kosina wrote:
> Now queued on top of the for-6.10/playstation pile in hid.git.

Thank you all!

Max