[bdf] Fix integer scanning routines.

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2029

* src/bdf/bdflib.c (_bdf_atoul, _bdf_atol, _bdf_atous, _bdf_atos):
Stop scanning if result would overflow.

ChangeLog

@@ -1,3 +1,14 @@
+2017-06-02  Werner Lemberg  <wl@gnu.org>
+
+	[bdf] Fix integer scanning routines.
+
+	Reported as
+
+	  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2029
+
+	* src/bdf/bdflib.c (_bdf_atoul, _bdf_atol, _bdf_atous, _bdf_atos):
+	Stop scanning if result would overflow.
+
 2017-06-02  Werner Lemberg  <wl@gnu.org>
 
 	[cff] Fix integer overflows.

src/bdf/bdflib.c

@@ -704,7 +704,15 @@
       return 0;
 
     for ( v = 0; sbitset( ddigits, *s ); s++ )
-      v = v * 10 + a2i[(int)*s];
+    {
+      if ( v < ( ULONG_MAX - 9 ) / 10 )
+        v = v * 10 + a2i[(int)*s];
+      else
+      {
+        v = ULONG_MAX;
+        break;
+      }
+    }
 
     return v;
   }
@@ -729,7 +737,15 @@
     }
 
     for ( v = 0; sbitset( ddigits, *s ); s++ )
-      v = v * 10 + a2i[(int)*s];
+    {
+      if ( v < ( LONG_MAX - 9 ) / 10 )
+        v = v * 10 + a2i[(int)*s];
+      else
+      {
+        v = LONG_MAX;
+        break;
+      }
+    }
 
     return ( !neg ) ? v : -v;
   }
@@ -746,7 +762,15 @@
       return 0;
 
     for ( v = 0; sbitset( ddigits, *s ); s++ )
-      v = (unsigned short)( v * 10 + a2i[(int)*s] );
+    {
+      if ( v < ( USHRT_MAX - 9 ) / 10 )
+        v = (unsigned short)( v * 10 + a2i[(int)*s] );
+      else
+      {
+        v = USHRT_MAX;
+        break;
+      }
+    }
 
     return v;
   }
@@ -771,7 +795,15 @@
     }
 
     for ( v = 0; sbitset( ddigits, *s ); s++ )
-      v = (short)( v * 10 + a2i[(int)*s] );
+    {
+      if ( v < ( SHRT_MAX - 9 ) / 10 )
+        v = (short)( v * 10 + a2i[(int)*s] );
+      else
+      {
+        v = SHRT_MAX;
+        break;
+      }
+    }
 
     return (short)( ( !neg ) ? v : -v );
   }