netdev - [PATCH 04/26] tty: kbd: reduce stack size with KASAN

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Date:   Thu,  2 Mar 2017 17:38:12 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     kasan-dev@...glegroups.com
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-wireless@...r.kernel.org,
        kernel-build-reports@...ts.linaro.org,
        "David S . Miller" <davem@...emloft.net>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 04/26] tty: kbd: reduce stack size with KASAN

As reported by kernelci, some functions in the VT code use significant
amounts of kernel stack when local variables get inlined into the caller
multiple times:

drivers/tty/vt/keyboard.c: In function 'kbd_keycode':
drivers/tty/vt/keyboard.c:1452:1: error: the frame size of 2240 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

Annotating those functions as noinline_for_kasan prevents the inlining
and reduces the overall stack usage in this driver.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/tty/vt/keyboard.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 397e1509fe51..f8a183c1639f 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -300,13 +300,13 @@ int kbd_rate(struct kbd_repeat *rpt)
 /*
  * Helper Functions.
  */
-static void put_queue(struct vc_data *vc, int ch)
+static noinline_for_kasan void put_queue(struct vc_data *vc, int ch)
 {
 	tty_insert_flip_char(&vc->port, ch, 0);
 	tty_schedule_flip(&vc->port);
 }
 
-static void puts_queue(struct vc_data *vc, char *cp)
+static noinline_for_kasan void puts_queue(struct vc_data *vc, char *cp)
 {
 	while (*cp) {
 		tty_insert_flip_char(&vc->port, *cp, 0);
@@ -554,7 +554,7 @@ static void fn_inc_console(struct vc_data *vc)
 	set_console(i);
 }
 
-static void fn_send_intr(struct vc_data *vc)
+static noinline_for_kasan void fn_send_intr(struct vc_data *vc)
 {
 	tty_insert_flip_char(&vc->port, 0, TTY_BREAK);
 	tty_schedule_flip(&vc->port);
-- 
2.9.0