[PATCH] Termio userspace access error handling

The attached patch creates a generic set of termio userspace access functions
with proper error handling.  None of the current archs check for errors in
this case.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-generic/termios.h

+/* termios.h: generic termios/termio user copying/translation
+ */
+
+#ifndef _ASM_GENERIC_TERMIOS_H
+#define _ASM_GENERIC_TERMIOS_H
+
+#include <asm/uaccess.h>
+
+#ifndef __ARCH_TERMIO_GETPUT
+
+/*
+ * Translate a "termio" structure into a "termios". Ugh.
+ */
+static inline int user_termio_to_kernel_termios(struct termios *termios,
+						struct termio __user *termio)
+{
+	unsigned short tmp;
+
+	if (get_user(tmp, &termio->c_iflag) < 0)
+		goto fault;
+	termios->c_iflag = (0xffff0000 & termios->c_iflag) | tmp;
+
+	if (get_user(tmp, &termio->c_oflag) < 0)
+		goto fault;
+	termios->c_oflag = (0xffff0000 & termios->c_oflag) | tmp;
+
+	if (get_user(tmp, &termio->c_cflag) < 0)
+		goto fault;
+	termios->c_cflag = (0xffff0000 & termios->c_cflag) | tmp;
+
+	if (get_user(tmp, &termio->c_lflag) < 0)
+		goto fault;
+	termios->c_lflag = (0xffff0000 & termios->c_lflag) | tmp;
+
+	if (get_user(termios->c_line, &termio->c_line) < 0)
+		goto fault;
+
+	if (copy_from_user(termios->c_cc, termio->c_cc, NCC) != 0)
+		goto fault;
+
+	return 0;
+
+ fault:
+	return -EFAULT;
+}
+
+/*
+ * Translate a "termios" structure into a "termio". Ugh.
+ */
+static inline int kernel_termios_to_user_termio(struct termio __user *termio,
+						struct termios *termios)
+{
+	if (put_user(termios->c_iflag, &termio->c_iflag) < 0 ||
+	    put_user(termios->c_oflag, &termio->c_oflag) < 0 ||
+	    put_user(termios->c_cflag, &termio->c_cflag) < 0 ||
+	    put_user(termios->c_lflag, &termio->c_lflag) < 0 ||
+	    put_user(termios->c_line,  &termio->c_line) < 0 ||
+	    copy_to_user(termio->c_cc, termios->c_cc, NCC) != 0)
+		return -EFAULT;
+
+	return 0;
+}
+
+#define user_termios_to_kernel_termios(k, u) copy_from_user(k, u, sizeof(struct termios))
+#define kernel_termios_to_user_termios(u, k) copy_to_user(u, k, sizeof(struct termios))
+
+#endif	/* __ARCH_TERMIO_GETPUT */
+
+#endif /* _ASM_GENERIC_TERMIOS_H */