CVE-2017-15670: glob: Fix one-byte overflow [BZ #22320]

ChangeLog

@@ -1,3 +1,9 @@
+2017-10-20  Paul Eggert <eggert@cs.ucla.edu>
+
+	[BZ #22320]
+	CVE-2017-15670
+	* posix/glob.c (__glob): Fix one-byte overflow.
+
 2017-10-20  Wilco Dijkstra  <wdijkstr@arm.com>
 
 	* malloc/malloc.c (sysdep-cancel.h): Add include.

NEWS

@@ -72,6 +72,10 @@ Security related changes:
   vulnerability; only trusted binaries must be examined using the ldd
   script.)
 
+  CVE-2017-15670: The glob function, when invoked with GLOB_TILDE, suffered
+  from a one-byte overflow during ~ operator processing (either on the stack
+  or the heap, depending on the length of the user name).
+
 The following bugs are resolved with this release:
 
   [The release manager will add the list generated by

posix/glob.c

@@ -790,7 +790,7 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		  *p = '\0';
 		}
 	      else
-		*((char *) mempcpy (newp, dirname + 1, end_name - dirname))
+		*((char *) mempcpy (newp, dirname + 1, end_name - dirname - 1))
 		  = '\0';
 	      user_name = newp;
 	    }