soc: qcom: cmd-db: replace deprecated strncpy with strtomem

strncpy() is an ambiguous and potentially dangerous interface [1]. We
should prefer more robust and less ambiguous alternatives.

@query is marked as __nonstring and doesn't need to be NUL-terminated.

Since we are doing a string to memory copy, we can use the aptly named
"strtomem" -- specifically, the "pad" variant to also ensure NUL-padding
throughout the destination buffer.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240319-strncpy-drivers-soc-qcom-cmd-db-c-v3-1-aeb5c5180c32@google.comSigned-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/soc/qcom/cmd-db.c

@@ -153,12 +153,7 @@ static int cmd_db_get_header(const char *id, const struct entry_header **eh,
 	if (ret)
 		return ret;
 
-	/*
-	 * Pad out query string to same length as in DB. NOTE: the output
-	 * query string is not necessarily '\0' terminated if it bumps up
-	 * against the max size. That's OK and expected.
-	 */
-	strncpy(query, id, sizeof(query));
+	strtomem_pad(query, id, 0);
 
 	for (i = 0; i < MAX_SLV_ID; i++) {
 		rsc_hdr = &cmd_db_header->header[i];