TTY: ttyprintk, don't touch behind tty->write_buf

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: stable@vger.kernel.org (everything maintained past v2.6.37)
Cc: Samo Pogacnik <samo_pogacnik@t-2.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index 9b1e5e0cdc6..08755c52fc5 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':