firmware: cs_dsp: Fix OOB memory read access in KUnit test (wmfw info)

KASAN reported out of bounds access - cs_dsp_mock_wmfw_add_info(),
because the source string length was rounded up to the allocation size.

Cc: Simon Trimmer <[email protected]>
Cc: Charles Keepax <[email protected]>
Cc: Richard Fitzgerald <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Jaroslav Kysela <[email protected]>
Reviewed-by: Richard Fitzgerald <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: perexg

drivers/firmware/cirrus/test/cs_dsp_mock_wmfw.c

@@ -133,10 +133,11 @@ void cs_dsp_mock_wmfw_add_info(struct cs_dsp_mock_wmfw_builder *builder,
 
 	if (info_len % 4) {
 		/* Create a padded string with length a multiple of 4 */
+		size_t copy_len = info_len;
 		info_len = round_up(info_len, 4);
 		tmp = kunit_kzalloc(builder->test_priv->test, info_len, GFP_KERNEL);
 		KUNIT_ASSERT_NOT_ERR_OR_NULL(builder->test_priv->test, tmp);
-		memcpy(tmp, info, info_len);
+		memcpy(tmp, info, copy_len);
 		info = tmp;
 	}