* Sanitize message headers by stripping high-ascii characters

  before handing them off to libSieve.  Otherwise, certain
  badly-formed messages (usually spam) will cause libSieve to
  clobber the stack, which was crashing Citadel.

diff --git a/citadel/serv_sieve.c b/citadel/serv_sieve.c
index b8af8e574953ae2969e0bc66eb6a938357c41468..8bfd7828b131392de4ad93a6feb35fa63385e9ee 100644 (file)
--- a/citadel/serv_sieve.c
+++ b/citadel/serv_sieve.c
@@ -12,7 +12,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <fcntl.h>
-#include <signal.h>
+#include <ctype.h>
 #include <pwd.h>
 #include <errno.h>
 #include <sys/types.h>
@@ -462,7 +462,6 @@ int ctdl_getheaders(sieve2_context_t *s, void *my) {
        struct ctdl_sieve *cs = (struct ctdl_sieve *)my;
 
        lprintf(CTDL_DEBUG, "ctdl_getheaders() was called\n");
-
        sieve2_setvalue_string(s, "allheaders", cs->rfc822headers);
        return SIEVE2_OK;
 }
@@ -496,21 +495,38 @@ void sieve_do_msg(long msgnum, void *userdata) {
        struct ctdl_sieve my;
        int res;
        struct CtdlMessage *msg;
+       int i;
+       size_t headers_len = 0;
 
        lprintf(CTDL_DEBUG, "Performing sieve processing on msg <%ld>\n", msgnum);
 
        msg = CtdlFetchMessage(msgnum, 0);
        if (msg == NULL) return;
 
+       /*
+        * Grab the message headers so we can feed them to libSieve.
+        */
        CC->redirect_buffer = malloc(SIZ);
        CC->redirect_len = 0;
        CC->redirect_alloc = SIZ;
        CtdlOutputPreLoadedMsg(msg, MT_RFC822, HEADERS_ONLY, 0, 1);
        my.rfc822headers = CC->redirect_buffer;
+       headers_len = CC->redirect_len;
        CC->redirect_buffer = NULL;
        CC->redirect_len = 0;
        CC->redirect_alloc = 0;
 
+       /*
+        * libSieve clobbers the stack if it encounters badly formed
+        * headers.  Sanitize our headers by stripping nonprintable
+        * characters.
+        */
+       for (i=0; i<headers_len; ++i) {
+               if (!isascii(my.rfc822headers[i])) {
+                       my.rfc822headers[i] = '_';
+               }
+       }
+
        my.keep = 0;                            /* Set to 1 to declare an *explicit* keep */
        my.cancel_implicit_keep = 0;            /* Some actions will cancel the implicit keep */
        my.usernum = atol(CC->room.QRname);     /* Keep track of the owner of the room's namespace */