Prevent use of uninitialized file lock

The CHECK_INIT() is necessary before the _newlib_flockfile_start() since
this would use otherwise acquire an uninitialized lock which gets
initialized after this leading to a corrupt release.

newlib/ChangeLog
2015-07-01  Sebastian Huber  <sebastian.huber@embedded-brains.de>

	libc/stdio/fputs.c (_puts_r): Add missing CHECK_INIT().
	libc/stdio/gets.c (_gets_r): Add missing _REENT_SMALL_CHECK_INIT() and
	CHECK_INIT().  Use _stdin_r() to get the file pointer instead of stdin.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

1 files changed, 8 insertions, 4 deletions

diff --git a/newlib/libc/stdio/gets.c b/newlib/libc/stdio/gets.c
index f51d46196..6c21f3e0c 100644
--- a/newlib/libc/stdio/gets.c
+++ b/newlib/libc/stdio/gets.c
@@ -79,13 +79,17 @@ _DEFUN(_gets_r, (ptr, buf),
 {
   register int c;
   register char *s = buf;
+  FILE *fp;
 
-  _newlib_flockfile_start (stdin);
-  while ((c = __sgetc_r (ptr, stdin)) != '\n')
+  _REENT_SMALL_CHECK_INIT (ptr);
+  fp = _stdin_r (ptr);
+  CHECK_INIT (ptr, fp);
+  _newlib_flockfile_start (fp);
+  while ((c = __sgetc_r (ptr, fp)) != '\n')
     if (c == EOF)
       if (s == buf)
 	{
-	  _newlib_flockfile_exit (stdin);
+	  _newlib_flockfile_exit (fp);
 	  return NULL;
 	}
       else
@@ -93,7 +97,7 @@ _DEFUN(_gets_r, (ptr, buf),
     else
       *s++ = c;
   *s = 0;
-  _newlib_flockfile_end (stdin);
+  _newlib_flockfile_end (fp);
   return buf;
 }