From 49167eecdec7620e15678f7a0ac30c4e8e4b32db Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Tue, 7 Aug 2012 21:47:39 +0200
Subject: [PATCH] TTY: ttyprintk, don't touch behind tty->write_buf

commit ee8b593affdf893012e57f4c54a21984d1b0d92e upstream.

If a user provides a buffer larger than a tty->write_buf chunk and
passes '\r' at the end of the buffer, we touch an out-of-bound memory.

Add a check there to prevent this.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Samo Pogacnik <samo_pogacnik@t-2.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/char/ttyprintk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index eedd5474850c..59366915eee2 100644
--- a/drivers/char/ttyprintk.c
+++ b/drivers/char/ttyprintk.c
@@ -67,7 +67,7 @@ static int tpk_printk(const unsigned char *buf, int count)
 				tmp[tpk_curr + 1] = '\0';
 				printk(KERN_INFO "%s%s", tpk_tag, tmp);
 				tpk_curr = 0;
-				if (buf[i + 1] == '\n')
+				if ((i + 1) < count && buf[i + 1] == '\n')
 					i++;
 				break;
 			case '\n':
-- 
2.39.5