Fix $regex<n> use-after-free. Bug 2915

[exim.git] / src / src / regex.c

diff --git a/src/src/regex.c b/src/src/regex.c
index 5c0f7c4e097dec55878208612703de54f8fe93b2..25496f950db7d09debf46c15f902dda139965238 100644 (file)
--- a/src/src/regex.c
+++ b/src/src/regex.c
@@ -18,9 +18,9 @@
 
 /* Structure to hold a list of Regular expressions */
 typedef struct pcre_list {
-  pcre2_code *re;
-  uschar *pcre_text;
-  struct pcre_list *next;
+  const pcre2_code *   re;
+  uschar *             pcre_text;
+  struct pcre_list *   next;
 } pcre_list;
 
 uschar regex_match_string_buffer[1024];
@@ -28,31 +28,27 @@ uschar regex_match_string_buffer[1024];
 extern FILE *mime_stream;
 extern uschar *mime_current_boundary;
 
+
 static pcre_list *
-compile(const uschar * list)
+compile(const uschar * list, BOOL cacheable)
 {
 int sep = 0;
-uschar *regex_string;
-pcre_list *re_list_head = NULL;
-pcre_list *ri;
+uschar * regex_string;
+pcre_list * re_list_head = NULL;
+pcre_list * ri;
 
 /* precompile our regexes */
 while ((regex_string = string_nextinlist(&list, &sep, NULL, 0)))
   if (strcmpic(regex_string, US"false") != 0 && Ustrcmp(regex_string, "0") != 0)
     {
-    pcre2_code * re;
-    int err;
-    PCRE2_SIZE pcre_erroffset;
-
     /* compile our regular expression */
-    if (!(re = pcre2_compile( (PCRE2_SPTR) regex_string, PCRE2_ZERO_TERMINATED,
-                 0, &err, &pcre_erroffset, pcre_cmp_ctx)))
+    uschar * errstr;
+    const pcre2_code * re = regex_compile(regex_string,
+      cacheable ? MCS_CACHEABLE : MCS_NOFLAGS, &errstr, pcre_gen_cmp_ctx);
+
+    if (!re)
       {
-      uschar errbuf[128];
-      pcre2_get_error_message(err, errbuf, sizeof(errbuf));
-      log_write(0, LOG_MAIN,
-          "regex acl condition warning - error in regex '%s': %s at offset %ld, skipped.",
-          regex_string, errbuf, (long)pcre_erroffset);
+      log_write(0, LOG_MAIN, "regex acl condition warning - %s, skipped", errstr);
       continue;
       }
 
@@ -75,7 +71,7 @@ for (pcre_list * ri = re_list_head; ri; ri = ri->next)
   int n;
 
   /* try matcher on the line */
-  if ((n = pcre2_match(ri->re, (PCRE2_SPTR)linebuffer, len, 0, 0, md, pcre_mtc_ctx)) > 0)
+  if ((n = pcre2_match(ri->re, (PCRE2_SPTR)linebuffer, len, 0, 0, md, pcre_gen_mtc_ctx)) > 0)
     {
     Ustrncpy(regex_match_string_buffer, ri->pcre_text,
              sizeof(regex_match_string_buffer)-1);
@@ -85,29 +81,39 @@ for (pcre_list * ri = re_list_head; ri; ri = ri->next)
       {
       PCRE2_UCHAR * cstr;
       PCRE2_SIZE cslen;
-      pcre2_substring_get_bynumber(md, nn, &cstr, &cslen);
+      pcre2_substring_get_bynumber(md, nn, &cstr, &cslen);     /* uses same ctx as md */
       regex_vars[nn-1] = CUS cstr;
       }
 
     return OK;
     }
   }
-pcre2_match_data_free(md);
+/* pcre2_match_data_free(md);  gen ctx needs no free */
 return FAIL;
 }
 
+
+/* reset expansion variables */
+void
+regex_vars_clear(void)
+{
+regex_match_string = NULL;
+for (int i = 0; i < REGEX_VARS; i++) regex_vars[i] = NULL;
+}
+
+
+
 int
-regex(const uschar **listptr)
+regex(const uschar ** listptr, BOOL cacheable)
 {
 unsigned long mbox_size;
-FILE *mbox_file;
-pcre_list *re_list_head;
-uschar *linebuffer;
+FILE * mbox_file;
+pcre_list * re_list_head;
+uschar * linebuffer;
 long f_pos = 0;
 int ret = FAIL;
 
-/* reset expansion variable */
-regex_match_string = NULL;
+regex_vars_clear();
 
 if (!mime_stream)                              /* We are in the DATA ACL */
   {
@@ -130,7 +136,7 @@ else
   }
 
 /* precompile our regexes */
-if (!(re_list_head = compile(*listptr)))
+if (!(re_list_head = compile(*listptr, cacheable)))
   return FAIL;                 /* no regexes -> nothing to do */
 
 /* match each line against all regexes */
@@ -167,19 +173,18 @@ return ret;
 
 
 int
-mime_regex(const uschar **listptr)
+mime_regex(const uschar **listptr, BOOL cacheable)
 {
-pcre_list *re_list_head = NULL;
-FILE *f;
-uschar *mime_subject = NULL;
+pcre_list * re_list_head = NULL;
+FILE * f;
+uschar * mime_subject = NULL;
 int mime_subject_len = 0;
 int ret;
 
-/* reset expansion variable */
-regex_match_string = NULL;
+regex_vars_clear();
 
 /* precompile our regexes */
-if (!(re_list_head = compile(*listptr)))
+if (!(re_list_head = compile(*listptr, cacheable)))
   return FAIL;                 /* no regexes -> nothing to do */
 
 /* check if the file is already decoded */