crypto: qat - Fix ADF_DEV_RESET_SYNC memory leak

commit d3b17c6d9dddc2db3670bc9be628b122416a3d26 upstream.

Using completion_done to determine whether the caller has gone
away only works after a complete call.  Furthermore it's still
possible that the caller has not yet called wait_for_completion,
resulting in another potential UAF.

Fix this by making the caller use cancel_work_sync and then freeing
the memory safely.

Fixes: 7d42e097607c ("crypto: qat - resolve race condition during AER recovery")
Cc: <stable@vger.kernel.org> #6.8+
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/crypto/qat/qat_common/adf_aer.c

@@ -95,8 +95,7 @@ static void adf_device_reset_worker(struct work_struct *work)
 	if (adf_dev_init(accel_dev) || adf_dev_start(accel_dev)) {
 		/* The device hanged and we can't restart it so stop here */
 		dev_err(&GET_DEV(accel_dev), "Restart device failed\n");
-		if (reset_data->mode == ADF_DEV_RESET_ASYNC ||
-		    completion_done(&reset_data->compl))
+		if (reset_data->mode == ADF_DEV_RESET_ASYNC)
 			kfree(reset_data);
 		WARN(1, "QAT: device restart failed. Device is unusable\n");
 		return;
@@ -104,16 +103,8 @@ static void adf_device_reset_worker(struct work_struct *work)
 	adf_dev_restarted_notify(accel_dev);
 	clear_bit(ADF_STATUS_RESTARTING, &accel_dev->status);
 
-	/*
-	 * The dev is back alive. Notify the caller if in sync mode
-	 *
-	 * If device restart will take a more time than expected,
-	 * the schedule_reset() function can timeout and exit. This can be
-	 * detected by calling the completion_done() function. In this case
-	 * the reset_data structure needs to be freed here.
-	 */
-	if (reset_data->mode == ADF_DEV_RESET_ASYNC ||
-	    completion_done(&reset_data->compl))
+	/* The dev is back alive. Notify the caller if in sync mode */
+	if (reset_data->mode == ADF_DEV_RESET_ASYNC)
 		kfree(reset_data);
 	else
 		complete(&reset_data->compl);
@@ -148,10 +139,10 @@ static int adf_dev_aer_schedule_reset(struct adf_accel_dev *accel_dev,
 		if (!timeout) {
 			dev_err(&GET_DEV(accel_dev),
 				"Reset device timeout expired\n");
+			cancel_work_sync(&reset_data->reset_work);
 			ret = -EFAULT;
-		} else {
-			kfree(reset_data);
 		}
+		kfree(reset_data);
 		return ret;
 	}
 	return 0;