From: Eric Covener <covener@apache.org>
Date: Fri, 5 Jun 2026 10:17:58 +0000 (+0000)
Subject: ap_regname: restrict to reasonable captures
X-Git-Url: http://git.ipfire.org/index.cgi?a=commitdiff_plain;h=52cb79b19e110bdd42bffc696844f801fb3c4a2d;p=thirdparty%2Fapache%2Fhttpd.git

ap_regname: restrict to reasonable captures


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1935014 13f79535-47bb-0310-9956-ffa450edef68
---

diff --git a/include/ap_regex.h b/include/ap_regex.h
index a986194151..6ed47a5195 100644
--- a/include/ap_regex.h
+++ b/include/ap_regex.h
@@ -228,6 +228,8 @@ AP_DECLARE(apr_size_t) ap_regerror(int errcode, const ap_regex_t *preg,
  * @param prefix An optional prefix to add to the returned names.  AP_REG_MATCH
  * is the recommended prefix.
  * @param upper If non zero, uppercase the names
+ * @return number of regex backrefernces returned, -1 for error
+ *         for successful match, AP_REG_NOMATCH otherwise
  */
 AP_DECLARE(int) ap_regname(const ap_regex_t *preg,
                            apr_array_header_t *names, const char *prefix,
diff --git a/modules/proxy/mod_proxy.c b/modules/proxy/mod_proxy.c
index 46d3b07145..3c2a28d925 100644
--- a/modules/proxy/mod_proxy.c
+++ b/modules/proxy/mod_proxy.c
@@ -2945,7 +2945,9 @@ static const char *proxysection(cmd_parms *cmd, void *mconfig, const char *arg)
 
     if (r) {
         conf->refs = apr_array_make(cmd->pool, 8, sizeof(char *));
-        ap_regname(r, conf->refs, AP_REG_MATCH, 1);
+        if (ap_regname(r, conf->refs, AP_REG_MATCH, 1) < 0) {
+            return "Error processing regex captures";
+        }
     }
 
     ap_add_per_proxy_conf(cmd->server, new_dir_conf);
diff --git a/server/core.c b/server/core.c
index 1dad12348c..315d6b5bac 100644
--- a/server/core.c
+++ b/server/core.c
@@ -2600,7 +2600,9 @@ static const char *dirsection(cmd_parms *cmd, void *mconfig, const char *arg)
 
     if (cmd->regex) {
         conf->refs = apr_array_make(cmd->pool, 8, sizeof(char *));
-        ap_regname(cmd->regex, conf->refs, AP_REG_MATCH, 1);
+        if (ap_regname(cmd->regex, conf->refs, AP_REG_MATCH, 1) < 0) {
+            return "Error processing regex captures";
+        }
     }
 
     /* Make this explicit - the "/" root has 0 elements, that is, we
@@ -2685,7 +2687,9 @@ static const char *urlsection(cmd_parms *cmd, void *mconfig, const char *arg)
 
     if (cmd->regex) {
         conf->refs = apr_array_make(cmd->pool, 8, sizeof(char *));
-        ap_regname(cmd->regex, conf->refs, AP_REG_MATCH, 1);
+        if (ap_regname(cmd->regex, conf->refs, AP_REG_MATCH, 1) < 0) {
+            return "Error processing regex captures";
+        }
     }
 
     ap_add_per_url_conf(cmd->server, new_url_conf);
@@ -2776,7 +2780,9 @@ static const char *filesection(cmd_parms *cmd, void *mconfig, const char *arg)
 
     if (cmd->regex) {
         conf->refs = apr_array_make(cmd->pool, 8, sizeof(char *));
-        ap_regname(cmd->regex, conf->refs, AP_REG_MATCH, 1);
+        if (ap_regname(cmd->regex, conf->refs, AP_REG_MATCH, 1) < 0) {
+            return "Error processing regex captures";
+        }
     }
 
     ap_add_file_conf(cmd->pool, (core_dir_config *)mconfig, new_file_conf);
diff --git a/server/util_pcre.c b/server/util_pcre.c
index f8817d2896..3c1dc8b2ff 100644
--- a/server/util_pcre.c
+++ b/server/util_pcre.c
@@ -590,7 +590,16 @@ AP_DECLARE(int) ap_regname(const ap_regex_t *preg,
 
     for (i = 0; i < namecount; i++) {
         const char *offset = nametable + i * nameentrysize;
-        int capture = ((offset[0] << 8) + offset[1]);
+        int capture = (((unsigned char)offset[0] << 8) + (unsigned char)offset[1]);
+        
+        /* Sanity check: reject unreasonably large capture group numbers.
+         * PCRE allows up to 65535 groups, but such large numbers would
+         * cause excessive memory allocation. Limit to a reasonable maximum.
+         */
+        if (capture > 1024) {
+            return -1;
+        }
+        
         while (names->nelts <= capture) {
             apr_array_push(names);
         }