[<prev] [next>] [day] [month] [year] [list]
Message-Id: <20170802111151.1818472-1-arnd@arndb.de>
Date: Wed, 2 Aug 2017 13:11:39 +0200
From: Arnd Bergmann <arnd@...db.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Arnd Bergmann <arnd@...db.de>, Rob Herring <robh@...nel.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH, urgent, tty-next] tty: fix __tty_insert_flip_char regression
Sergey noticed a small but fatal mistake in __tty_insert_flip_char,
leading to an oops in an interrupt handler when using any serial
port.
The problem is that I accidentally took the tty_buffer pointer
before calling __tty_buffer_request_room(), which replaces the
buffer. This moves the pointer lookup to the right place after
allocating the new buffer space.
Fixes: 979990c62848 ("tty: improve tty_insert_flip_char() fast path")
Reported-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
drivers/tty/tty_buffer.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 6a8563633d4b..f8eba1c5412f 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -372,12 +372,13 @@ EXPORT_SYMBOL(tty_insert_flip_string_flags);
*/
int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag)
{
- struct tty_buffer *tb = port->buf.tail;
+ struct tty_buffer *tb;
int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;
if (!__tty_buffer_request_room(port, 1, flags))
return 0;
+ tb = port->buf.tail;
if (~tb->flags & TTYB_NORMAL)
*flag_buf_ptr(tb, tb->used) = flag;
*char_buf_ptr(tb, tb->used++) = ch;
--
2.9.0
Powered by blists - more mailing lists