CVE-2021-46784 (published 2022-07-17T22:15Z)

In Squid 3.x through 3.5.28, 4.x through 4.17, and 5.x before 5.6, due to improper buffer management, a Denial of Service can occur when processing long Gopher server responses.

CVSS v3 base score: 6.5, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-617
cwe_name: Reachable Assertion
description: The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
extended_description: 
            While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service.
            For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.
         
         

Fix information:
repo_url: https://github.com/squid-cache/squid
commit_details: repo_url: https://github.com/squid-cache/squid
author: Joshua Rogers
author_date: 2022-04-18 13:42:36+00:00
msg: Improve handling of Gopher responses (#1022)
repository: repo_url: https://github.com/squid-cache/squid
repo_name: squid-cache/squid
description: Squid Web Proxy Cache
repo_language: C++
owner: squid-cache
file_changes: filename: gopher.cc
change_type: ModificationType.MODIFY
diff: @@ -365,7 +365,6 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
     char *lpos = NULL;
     char *tline = NULL;
     LOCAL_ARRAY(char, line, TEMP_BUF_SIZE);
-    LOCAL_ARRAY(char, tmpbuf, TEMP_BUF_SIZE);
     char *name = NULL;
     char *selector = NULL;
     char *host = NULL;
@@ -375,7 +374,6 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
     char gtype;
     StoreEntry *entry = NULL;
 
-    memset(tmpbuf, '\0', TEMP_BUF_SIZE);
     memset(line, '\0', TEMP_BUF_SIZE);
 
     entry = gopherState->entry;
@@ -410,7 +408,7 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
         return;
     }
 
-    String outbuf;
+    SBuf outbuf;
 
     if (!gopherState->HTML_header_added) {
         if (gopherState->conversion == GopherStateData::HTML_CSO_RESULT)
@@ -582,37 +580,34 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
                         break;
                     }
 
-                    memset(tmpbuf, '\0', TEMP_BUF_SIZE);
-
                     if ((gtype == GOPHER_TELNET) || (gtype == GOPHER_3270)) {
                         if (strlen(escaped_selector) != 0)
-                            snprintf(tmpbuf, TEMP_BUF_SIZE, "<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"telnet://%s@%s%s%s/\">%s</A>\n",
+                            outbuf.appendf("<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"telnet://%s@%s%s%s/\">%s</A>\n",
                                      icon_url, escaped_selector, rfc1738_escape_part(host),
                                      *port ? ":" : "", port, html_quote(name));
                         else
-                            snprintf(tmpbuf, TEMP_BUF_SIZE, "<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"telnet://%s%s%s/\">%s</A>\n",
+                            outbuf.appendf("<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"telnet://%s%s%s/\">%s</A>\n",
                                      icon_url, rfc1738_escape_part(host), *port ? ":" : "",
                                      port, html_quote(name));
 
                     } else if (gtype == GOPHER_INFO) {
-                        snprintf(tmpbuf, TEMP_BUF_SIZE, "\t%s\n", html_quote(name));
+                        outbuf.appendf("\t%s\n", html_quote(name));
                     } else {
                         if (strncmp(selector, "GET /", 5) == 0) {
                             /* WWW link */
-                            snprintf(tmpbuf, TEMP_BUF_SIZE, "<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"http://%s/%s\">%s</A>\n",
+                            outbuf.appendf("<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"http://%s/%s\">%s</A>\n",
                                      icon_url, host, rfc1738_escape_unescaped(selector + 5), html_quote(name));
                         } else if (gtype == GOPHER_WWW) {
-                            snprintf(tmpbuf, TEMP_BUF_SIZE, "<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"%s\">%s</A>\n",
+                            outbuf.appendf("<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"gopher://%s/%c%s\">%s</A>\n",
                                      icon_url, rfc1738_escape_unescaped(selector), html_quote(name));
                         } else {
                             /* Standard link */
-                            snprintf(tmpbuf, TEMP_BUF_SIZE, "<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"gopher://%s/%c%s\">%s</A>\n",
+                            outbuf.appendf("<IMG border=\"0\" SRC=\"%s\"> <A HREF=\"gopher://%s/%c%s\">%s</A>\n",
                                      icon_url, host, gtype, escaped_selector, html_quote(name));
                         }
                     }
 
                     safe_free(escaped_selector);
-                    outbuf.append(tmpbuf);
                 } else {
                     memset(line, '\0', TEMP_BUF_SIZE);
                     continue;
@@ -645,13 +640,12 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
                     break;
 
                 if (gopherState->cso_recno != recno) {
-                    snprintf(tmpbuf, TEMP_BUF_SIZE, "</PRE><HR noshade size=\"1px\"><H2>Record# %d<br><i>%s</i></H2>\n<PRE>", recno, html_quote(result));
+                    outbuf.appendf("</PRE><HR noshade size=\"1px\"><H2>Record# %d<br><i>%s</i></H2>\n<PRE>", recno, html_quote(result));
                     gopherState->cso_recno = recno;
                 } else {
-                    snprintf(tmpbuf, TEMP_BUF_SIZE, "%s\n", html_quote(result));
+                    outbuf.appendf("%s\n", html_quote(result));
                 }
 
-                outbuf.append(tmpbuf);
                 break;
             } else {
                 int code;
@@ -679,8 +673,7 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
 
                 case 502: { /* Too Many Matches */
                     /* Print the message the server returns */
-                    snprintf(tmpbuf, TEMP_BUF_SIZE, "</PRE><HR noshade size=\"1px\"><H2>%s</H2>\n<PRE>", html_quote(result));
-                    outbuf.append(tmpbuf);
+                    outbuf.appendf("</PRE><HR noshade size=\"1px\"><H2>%s</H2>\n<PRE>", html_quote(result));
                     break;
                 }
 
@@ -696,13 +689,12 @@ gopherToHTML(GopherStateData * gopherState, char *inbuf, int len)
 
     }               /* while loop */
 
-    if (outbuf.size() > 0) {
-        entry->append(outbuf.rawBuf(), outbuf.size());
+    if (outbuf.length() > 0) {
+        entry->append(outbuf.rawContent(), outbuf.length());
         /* now let start sending stuff to client */
         entry->flush();
     }
 
-    outbuf.clean();
     return;
 }
 

programming_language: C