ASoC: Intel: avs: Verify content returned by parse_int_array()

The first element of the returned array stores its length. If it is 0,
any manipulation beyond the element at index 0 ends with null-ptr-deref.

Fixes: 5a565ba ("ASoC: Intel: avs: Probing and firmware tracing over debugfs")
Reviewed-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://patch.msgid.link/20250530141025.2942936-8-cezary.rojewski@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: crojewsk-intel

sound/soc/intel/avs/debugfs.c

@@ -373,14 +373,18 @@ static ssize_t trace_control_write(struct file *file, const char __user *from, s
 		return ret;
 
 	num_elems = *array;
-	resource_mask = array[1];
+	if (!num_elems) {
+		ret = -EINVAL;
+		goto free_array;
+	}
 
 	/*
 	 * Disable if just resource mask is provided - no log priority flags.
 	 *
 	 * Enable input format:   mask, prio1, .., prioN
 	 * Where 'N' equals number of bits set in the 'mask'.
 	 */
+	resource_mask = array[1];
 	if (num_elems == 1) {
 		ret = disable_logs(adev, resource_mask);
 	} else {