Fix invalid pointer dereference in wcpcpy_chk

The src pointer is const and points to a different object, so accessing
dest via src is invalid.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/debug/wcpcpy_chk.c b/debug/wcpcpy_chk.c
index bc2be43c3e..d44fb479d0 100644
--- a/debug/wcpcpy_chk.c
+++ b/debug/wcpcpy_chk.c
@@ -28,13 +28,12 @@ __wcpcpy_chk (wchar_t *dest, const wchar_t *src, size_t destlen)
 {
   wchar_t *wcp = (wchar_t *) dest - 1;
   wint_t c;
-  const ptrdiff_t off = src - dest + 1;
 
   do
     {
       if (__glibc_unlikely (destlen-- == 0))
 	__chk_fail ();
-      c = wcp[off];
+      c = *src++;
       *++wcp = c;
     }
   while (c != L'\0');