[GitHub] [trafficserver] masaori335 commented on a change in pull request #6950: Prevent buffer overflow during log filter actions

[GitBox <gi...@apache.org>]

masaori335 commented on a change in pull request #6950:
URL: https://github.com/apache/trafficserver/pull/6950#discussion_r448054921



##########
File path: proxy/logging/LogAccess.cc
##########
@@ -1162,7 +1162,7 @@ void
 LogAccess::set_client_req_unmapped_url_canon(char *buf, int len)
 {
   if (buf && m_client_req_unmapped_url_canon_str) {
-    m_client_req_unmapped_url_canon_len = len;
+    m_client_req_unmapped_url_canon_len = std::min(len, m_client_req_unmapped_url_canon_len);
     ink_strlcpy(m_client_req_unmapped_url_canon_str, buf, m_client_req_unmapped_url_canon_len + 1);

Review comment:
       I agree with this change fix the buffer overflow. 
   
   What I'm wondering is this function will call `ink_strlcpy` like below under the conditions.
   ```
   ink_strlcpy(INVALID_STR, buf, 1);
   ```
   It might not be harmful, but meaningless.
   
   The current checks in 1164 is only for nullptr. This doesn't work for `INVALID_STR`, right?
   It looks better to check `m_client_req_unmapped_url_canon_str` is `INVALID_STR` or not too.
   ```
   if (buf && m_client_req_unmapped_url_canon_str && m_client_req_unmapped_url_canon_str != INVALID_STR) {
   ```




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