lib: modem_key_mgmt: update modem_key_mgmt.c

Added support to return ENOMEM errno when buffer length doesnot
match certificate length

Signed-off-by: Nirmal Krishna <nirmal.rathakrishnan@nordicsemi.no>

doc/nrf/releases/release-notes-changelog.rst

@@ -337,6 +337,10 @@ Modem libraries
 
  * Updated the library to allow a ``PDP_type``-only configuration in the :c:func:`pdn_ctx_configure` function.
 
+* :ref:`nrf_modem_lib_readme`:
+
+ * Updated the :c:func:`modem_key_mgmt_cmp` function to return ``1`` if the buffer length does not match the certificate length.
+
 Libraries for networking
 ------------------------
 

lib/modem_key_mgmt/modem_key_mgmt.c

@@ -188,7 +188,7 @@ int modem_key_mgmt_cmp(nrf_sec_tag_t sec_tag,
  const void *buf, size_t len)
 {
  int err;
- char *p;
+ char *begin, *end;
 
  if (buf == NULL) {
  return -EINVAL;
@@ -199,16 +199,26 @@ int modem_key_mgmt_cmp(nrf_sec_tag_t sec_tag,
  return err;
  }
 
- p = scratch_buf;
+ begin = scratch_buf;
  for (size_t i = 0; i < 3; i++) {
- p = strchr(p, '\"');
- if (!p) {
+ begin = strchr(begin, '\"');
+ if (!begin) {
  return -ENOENT;
  }
- p++;
+ begin++;
+ }
+
+ end = strchr(begin, '\"');
+ if (!end) {
+ return -ENOENT;
+ }
+
+ if (end - begin != len) {
+ LOG_DBG("Credential length mismatch");
+ return 1;
  }
 
- if (memcmp(p, buf, len)) {
+ if (memcmp(begin, buf, len)) {
  LOG_DBG("Credential data mismatch");
  return 1;
  }