[PATCH 2/2] TTY: ntty, add one more sanoty check

[Jiri Slaby <jslaby@suse.cz>]

With the previous patch, we fixed another bug where read_buf was freed
while we still was in n_tty_read. We currently check whether read_buf
is NULL at the start of the function. Add one more check after we wake
up from waiting for input.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
---
 drivers/tty/n_tty.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 95d0a9c..c62c856 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1785,6 +1785,7 @@ do_it_again:
 				break;
 			}
 			timeout = schedule_timeout(timeout);
+			BUG_ON(!tty->read_buf);
 			continue;
 		}
 		__set_current_state(TASK_RUNNING);
-- 
1.7.5.3