mod_jserv/4901: ErrorDocument redirect to servlet causes crash

[Tim Zingelman <zi...@fnal.gov>]

>Number:         4901
>Category:       mod_jserv
>Synopsis:       ErrorDocument redirect to servlet causes crash
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    jserv
>State:          open
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Tue Aug 24 19:20:00 PDT 1999
>Last-Modified:
>Originator:     zingelman@fnal.gov
>Organization:
apache
>Release:        apache_1.3.6 + ApacheJServ-1.0
>Environment:
FreeBSD 3.2-STABLE, jdk1.1.8 (no jit)
>Description:
in mod_jserv.c:1495 if (strcasecmp(r->prev->handler,"jserv-action")==0),
r->prev->handler is null if we are redirected here via an ErrorDocument
directive (ie. ErrorDocument 404 /servlets/help) and this causes a crash.

[Tue Aug 24 18:00:38 1999] [notice] child pid 13535 exit signal Segmentation fault (11)

I'm not sure the full fix, but adding code to check r->prev->handler!=NULL but
then still assigning r->path_info=r->prev->uri got me what I needed.
>How-To-Repeat:
ErrorDocument 404 /servlets/trivialservlet
http://yourserver/non-existing-file.html
>Fix:
As above, yes at least in part.  I do need the path_info from the previous
request, to write a reasonable error servlet, but I have not dug deep enough
to know everything that is going on here... this is a diff -c

*** mod_jserv.c_orig    Tue Aug 24 20:59:34 1999
--- mod_jserv.c Tue Aug 24 21:10:40 1999
***************
*** 1491,1503 ****
                }
      /* If this was an internal redirection from Apache JServ then our path_info is
         previous uri */
!     if (r->prev!=NULL)
        if (strcasecmp(r->prev->handler,"jserv-action")==0) {
            /* Remove date header (FIX BUG: StringIndexOutOfBoundsException) */
            ap_table_unset(r->headers_in,"If-Modified-Since");
            r->path_info=r->prev->uri;
            r->filename=NULL;
        }

  
      /* Check if we have a per request or per server protocol and use it */
      if (req->mount->protocol!=NULL) proto=req->mount->protocol;
--- 1491,1509 ----
                }
      /* If this was an internal redirection from Apache JServ then our path_info is
         previous uri */
!     if (r->prev!=NULL) {
!       if (r->prev->handler!=NULL) {
        if (strcasecmp(r->prev->handler,"jserv-action")==0) {
            /* Remove date header (FIX BUG: StringIndexOutOfBoundsException) */
            ap_table_unset(r->headers_in,"If-Modified-Since");
            r->path_info=r->prev->uri;
            r->filename=NULL;
        }
+       }
+       if (r->prev->status==404) {
+       r->path_info=r->prev->uri;
+       }
+     }
  
      /* Check if we have a per request or per server protocol and use it */
      if (req->mount->protocol!=NULL) proto=req->mount->protocol;
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