Fix potential heap corruption in "gpg -v --version"

* g10/gpg.c (build_list): Rewrite to cope with buffer overflow in
certain locales.
* util/membuf.c (put_membuf_str): New.
(get_membuf): Make LEN optional.
--

This fixes an obvious bug in locales where the translated string is
longer than the original.  The bug could be exhibited by using
LANG=ru_RU.utf8 gpg -v --version.

En passant we also removed the trailing white space on continued
lines.

Reported-by: Dmitry V. Levin" <ldv at altlinux.org>

THANKS

@@ -49,6 +49,7 @@ David R. Bergstein         dbergstein@home.com
 David Shaw                 dshaw@jabberwocky.com
 Detlef Lannert		   lannert@lannert.rz.uni-duesseldorf.de
 Dimitri 		   dmitri@advantrix.com
+Dmitry V. Levin            ldv at altlinux dot org
 Dirk Lattermann 	   dlatt@t-online.de
 Dirk Meyer                 dirk.meyer@dinoex.sub.org
 Disastry                   Disastry@saiknes.lv

g10/gpg.c

@@ -838,54 +838,50 @@ static char *
 build_list (const char *text, char letter,
 	    const char * (*mapf)(int), int (*chkf)(int))
 {
-    int i;
+  membuf_t mb;
+  int indent;
+  int i, j, len;
   const char *s;
-    size_t n=strlen(text)+2;
-    char *list, *p, *line=NULL;
+  char *string;
 
   if (maybe_setuid)
-	secmem_init( 0 );    /* drop setuid */
+    secmem_init (0);    /* Drop setuid */
+
+  indent = strlen (text);
+  len = 0;
+  init_membuf (&mb, 512);
 
   for (i=0; i <= 110; i++ )
+    {
       if (!chkf (i) && (s = mapf (i)))
-	    n += strlen(s) + 7 + 2;
-    list = xmalloc( 21 + n ); *list = 0;
-    for(p=NULL, i=0; i <= 110; i++ ) {
-	if( !chkf(i) && (s=mapf(i)) ) {
-	    if( !p ) {
-		p = stpcpy( list, text );
-		line=p;
+        {
+          if (mb.len - len > 60)
+            {
+              put_membuf_str (&mb, ",\n");
+              len = mb.len;
+              for (j=0; j < indent; j++)
+                put_membuf_str (&mb, " ");
 	    }
+          else if (mb.len)
+            put_membuf_str (&mb, ", ");
           else
-		p = stpcpy( p, ", ");
+            put_membuf_str (&mb, text);
 
-	    if(strlen(line)>60) {
-	      int spaces=strlen(text);
-
-	      list=xrealloc(list,n+spaces+1);
-	      /* realloc could move the block, so find the end again */
-	      p=list;
-	      while(*p)
-		p++;
-
-	      p=stpcpy(p, "\n");
-	      line=p;
-	      for(;spaces;spaces--)
-		p=stpcpy(p, " ");
-	    }
-
-	    p = stpcpy(p, s );
+          put_membuf_str (&mb, s);
           if (opt.verbose && letter)
             {
-		char num[8];
-		sprintf(num," (%c%d)",letter,i);
-		p = stpcpy(p,num);
+              char num[20];
+              snprintf (num, sizeof num, " (%c%d)", letter, i);
+              put_membuf_str (&mb, num);
             }
 	}
     }
-    if( p )
-	p = stpcpy(p, "\n" );
-    return list;
+  if (mb.len)
+    put_membuf_str (&mb, "\n");
+  put_membuf (&mb, "", 1);
+
+  string = get_membuf (&mb, NULL);
+  return xrealloc (string, strlen (string)+1);
 }
 
 

include/util.h

@@ -219,6 +219,7 @@ typedef struct private_membuf_s membuf_t;
 
 void init_membuf (membuf_t *mb, int initiallen);
 void put_membuf  (membuf_t *mb, const void *buf, size_t len);
+void put_membuf_str (membuf_t *mb, const char *buf);
 void *get_membuf (membuf_t *mb, size_t *len);
 
 

util/membuf.c

@@ -62,6 +62,13 @@ put_membuf (membuf_t *mb, const void *buf, size_t len)
 }
 
 
+void
+put_membuf_str (membuf_t *mb, const char *buf)
+{
+  put_membuf (mb, buf, strlen (buf));
+}
+
+
 void *
 get_membuf (membuf_t *mb, size_t *len)
 {
@@ -75,6 +82,7 @@ get_membuf (membuf_t *mb, size_t *len)
     }
 
   p = mb->buf;
+  if (len)
     *len = mb->len;
   mb->buf = NULL;
   mb->out_of_core = ENOMEM; /* hack to make sure it won't get reused. */