firmware: cs_dsp: Use strnlen() on name fields in V1 wmfw files

Use strnlen() instead of strlen() on the algorithm and coefficient name
string arrays in V1 wmfw files.

In V1 wmfw files the name is a NUL-terminated string in a fixed-size
array. cs_dsp should protect against overrunning the array if the NUL
terminator is missing.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: f6bc909e ("firmware: cs_dsp: add driver to support firmware loading on Cirrus Logic DSPs")
Link: https://patch.msgid.link/20240708144855.385332-1-rf@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/firmware/cirrus/cs_dsp.c

@@ -1182,7 +1182,7 @@ static int cs_dsp_coeff_parse_alg(struct cs_dsp *dsp,
 
 		blk->id = le32_to_cpu(raw->id);
 		blk->name = raw->name;
-		blk->name_len = strlen(raw->name);
+		blk->name_len = strnlen(raw->name, ARRAY_SIZE(raw->name));
 		blk->ncoeff = le32_to_cpu(raw->ncoeff);
 
 		pos = sizeof(*raw);
@@ -1258,7 +1258,7 @@ static int cs_dsp_coeff_parse_coeff(struct cs_dsp *dsp,
 			return -EOVERFLOW;
 
 		blk->name = raw->name;
-		blk->name_len = strlen(raw->name);
+		blk->name_len = strnlen(raw->name, ARRAY_SIZE(raw->name));
 		blk->ctl_type = le16_to_cpu(raw->ctl_type);
 		blk->flags = le16_to_cpu(raw->flags);
 		blk->len = le32_to_cpu(raw->len);