[ 19/57] tty: Fix SIGTTOU not sent with tcflush()

[Greg Kroah-Hartman]

3.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>

commit 5cec7bf699c61d14f0538345076480bb8c8ebfbb upstream.

Commit 'e7f3880cd9b98c5bf9391ae7acdec82b75403776'
  tty: Fix recursive deadlock in tty_perform_flush()
introduced a regression where tcflush() does not generate
SIGTTOU for background process groups.

Make sure ioctl(TCFLSH) calls tty_check_change() when
invoked from the line discipline.

Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/tty/tty_ioctl.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -1201,6 +1201,9 @@ int n_tty_ioctl_helper(struct tty_struct
 		}
 		return 0;
 	case TCFLSH:
+		retval = tty_check_change(tty);
+		if (retval)
+			return retval;
 		return __tty_perform_flush(tty, arg);
 	default:
 		/* Try the mode commands */


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/