[patch] crash on multibyte editing in C locale

[Tim Waugh]

Configuration Information [Automatically generated, do not change]:
Machine: i386
OS: linux-gnu
Compiler: i386-redhat-linux-gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i386' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i386-redhat-linux-gnu' 
-DCONF_VENDOR='redhat' -DSHELL -DHAVE_CONFIG_H  -I.  -I. -I./include -I./lib 
-D_FILE_OFFSET_BITS=64 -O2 -g -pipe -march=i386 -mcpu=i686
uname output: Linux gene.surrey.redhat.com 2.4.22-1.2030.nptl #1 Sun Sep 7 
08:33:58 EDT 2003 i686 i686 i386 GNU/Linux
Machine Type: i386-redhat-linux-gnu

Bash Version: 2.05b
Patch Level: 0
Release Status: release

Description:
        https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=74266

        With multibyte history, but locale set to 'C', scrolling back
        through history and editing it can cause a segmentation
        fault.

Repeat-By:
        See bug report URL above (start at comment #14).

Fix:

--- bash-2.05b/lib/readline/mbutil.c.crash      2003-09-18 12:24:18.000000000 
+0100
+++ bash-2.05b/lib/readline/mbutil.c    2003-09-18 12:25:44.000000000 +0100
@@ -205,14 +205,14 @@
   if (tmp == (size_t)(-2))
     {
       /* shorted to compose multibyte char */
-      memset (ps, 0, sizeof(mbstate_t));
+      if (ps) memset (ps, 0, sizeof(mbstate_t));
       return -2;
     }
   else if (tmp == (size_t)(-1))
     {
       /* invalid to compose multibyte char */
       /* initialize the conversion state */
-      memset (ps, 0, sizeof(mbstate_t));
+      if (ps) memset (ps, 0, sizeof(mbstate_t));
       return -1;
     }
   else if (tmp == (size_t)0)
@@ -276,7 +276,7 @@
          pos++;
          /* clear the state of the byte sequence, because
             in this case effect of mbstate is undefined  */
-         memset (ps, 0, sizeof (mbstate_t));
+         if (ps) memset (ps, 0, sizeof (mbstate_t));
        }
       else
        pos += tmp;