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RE: Re: Unzip *ALL* verisons ;))
From: <Glenn.Everhart () chase com>
Date: Thu, 5 Jan 2006 08:33:16 -0500

There are or at least used to be limits to commandline args in VMS.
I seem to recall that for foreign commands the limit is 255 or 256;
nothing longer gets passed. This stuff has been in DCL for years.

Now, it is possible that recent versions might have extended this
limit, but it is very difficult in VMS to have anything of unbounded
size...too many internal calls work by descriptor, where a hard limit
is enforced, so the odd case that does not tends to be protected somewhat.


-----Original Message-----
From: full-disclosure-bounces () lists grok org uk
[mailto:full-disclosure-bounces () lists grok org uk]On Behalf Of Johnny
Lee
Sent: Wednesday, January 04, 2006 5:00 PM
To: full-disclosure () lists grok org uk
Subject: [Full-disclosure] Re: Unzip *ALL* verisons ;))


No one can compile unzip with debug info? :)

I looked at this on Windows. Unzip5.52 fixed a buffer overflow
in the do_wild() function in all the ports.

However, in vms\vms.c, there's still an unbounded strcpy call copying
wld to last_wild. I don't know if there are any bounds to command line
args in VMS, but if the first arg can be >256 chars, there's a buffer
overflow there.

In process.c, in process_zipfiles(), there's the following code:

           char *p = lastzipfn + strlen(lastzipfn);

           G.zipfn = lastzipfn;
           strcpy(p, ZSUFX);

The fix for the do_wild() buffer overflow was to cap the string at FILNAMSIZ
chars. So if we get to this point, then the strcpy of the ZSUFX will
cause a slight buffer overflow of lastzipfn which typically points to
G.matchname or a static matchname char array. It'd be really hard to
exploit too, but I'm just mentioning it.

The other possible buffer overflow is the Info macro in unzpriv.h.
Code would end up using sprintf() to the
slide array which is 32KB if MALLOC_WORK is NOT defined.

I can't repro a segfault/access violation in the Win32 version of
unzip 5.52 though unless I set the first argument to >32K via code. But you
cannot create a Win32 process with a command line longer than 32K for
WinXP+, (<= 2K on Win2K).

With the Win32 DLL, it'd be possible for an app to pass in an arg
that's >32K chars.

Maybe on Unix with an arg that is a lot larger than 32K chars.

Also a long environment variable may cause a buffer overflow.

Updating the Info macro to use snprintf() would be the 'correct' thing
to do. But all ports may not support snprintf() and the Info
macro is used in many places.

Adjusting all the uses of the Info macro to pass in the buffer size
would take a long time. Time to whip out your favourite scripting language
and write some code.

You can use the C runtime (if it's ANSI-compliant) to avoid the Info macro's
buffer overflow by passing a precision value for the string args.

Here's a quick patch - I arbitrarily chose 512 as the max chars displayed:

--- consts.old  Sat Mar 23 10:52:48 2002
+++ consts.h    Tue Jan 03 16:36:54 2006
@@ -34,9 +34,9 @@
  "error:  expected central file header signature not found (file #%lu).\n";
 ZCONST char Far SeekMsg[] =
  "error [%s]:  attempt to seek before beginning of zipfile\n%s";
-ZCONST char Far FilenameNotMatched[] = "caution: filename not matched:  %s\n";
+ZCONST char Far FilenameNotMatched[] = "caution: filename not
matched:  %.512s\n";
 ZCONST char Far ExclFilenameNotMatched[] =
-  "caution: excluded filename not matched:  %s\n";
+  "caution: excluded filename not matched:  %.512s\n";

 #ifdef VMS
  ZCONST char Far ReportMsg[] = "\
--- process.old Sun Nov 21 19:42:54 2004
+++ process.c   Tue Jan 03 16:56:48 2006
@@ -74,20 +74,20 @@
   /* do_seekable() strings */
 # ifdef UNIX
   static ZCONST char Far CannotFindZipfileDirMsg[] =
-     "%s:  cannot find zipfile directory in one of %s or\n\
-        %s%s.zip, and cannot find %s, period.\n";
+     "%s:  cannot find zipfile directory in one of %.512s or\n\
+        %s%.512s.zip, and cannot find %.512s, period.\n";
   static ZCONST char Far CannotFindEitherZipfile[] =
-     "%s:  cannot find or open %s, %s.zip or %s.\n";
+     "%s:  cannot find or open %.512s, %.512s.zip or %.512s.\n";
 # else /* !UNIX */
 # ifndef AMIGA
   static ZCONST char Far CannotFindWildcardMatch[] =
-     "%s:  cannot find any matches for wildcard specification \"%s\".\n";
+     "%s:  cannot find any matches for wildcard specification \"%.512s\".\n";
 # endif /* !AMIGA */
   static ZCONST char Far CannotFindZipfileDirMsg[] =
-     "%s:  cannot find zipfile directory in %s,\n\
-        %sand cannot find %s, period.\n";
+     "%s:  cannot find zipfile directory in %.512s,\n\
+        %sand cannot find %.512s, period.\n";
   static ZCONST char Far CannotFindEitherZipfile[] =
-     "%s:  cannot find either %s or %s.\n";
+     "%s:  cannot find either %.512s or %.512s.\n";
 # endif /* ?UNIX */
   extern ZCONST char Far Zipnfo[];       /* in unzip.c */
 #ifndef WINDLL

J
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