Patch "media: r820t: fix r820t_write_reg for KASAN" has been added to the 3.18-stable tree

Patch "media: r820t: fix r820t_write_reg for KASAN" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    media: r820t: fix r820t_write_reg for KASAN

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     media-r820t-fix-r820t_write_reg-for-kasan.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 16c3ada89cff9a8c2a0eea34ffa1aa20af3f6008 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Thu, 30 Nov 2017 06:08:05 -0500
Subject: media: r820t: fix r820t_write_reg for KASAN

From: Arnd Bergmann <arnd@arndb.de>

commit 16c3ada89cff9a8c2a0eea34ffa1aa20af3f6008 upstream.

With CONFIG_KASAN, we get an overly long stack frame due to inlining
the register access functions:

drivers/media/tuners/r820t.c: In function 'generic_set_freq.isra.7':
drivers/media/tuners/r820t.c:1334:1: error: the frame size of 2880 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

This is caused by a gcc bug that has now been fixed in gcc-8.
To work around the problem, we can pass the register data
through a local variable that older gcc versions can optimize
out as well.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/media/tuners/r820t.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/media/tuners/r820t.c
+++ b/drivers/media/tuners/r820t.c
@@ -410,9 +410,11 @@ static int r820t_write(struct r820t_priv
 	return 0;
 }
 
-static int r820t_write_reg(struct r820t_priv *priv, u8 reg, u8 val)
+static inline int r820t_write_reg(struct r820t_priv *priv, u8 reg, u8 val)
 {
-	return r820t_write(priv, reg, &val, 1);
+	u8 tmp = val; /* work around GCC PR81715 with asan-stack=1 */
+
+	return r820t_write(priv, reg, &tmp, 1);
 }
 
 static int r820t_read_cache_reg(struct r820t_priv *priv, int reg)
@@ -425,17 +427,18 @@ static int r820t_read_cache_reg(struct r
 		return -EINVAL;
 }
 
-static int r820t_write_reg_mask(struct r820t_priv *priv, u8 reg, u8 val,
+static inline int r820t_write_reg_mask(struct r820t_priv *priv, u8 reg, u8 val,
 				u8 bit_mask)
 {
+	u8 tmp = val;
 	int rc = r820t_read_cache_reg(priv, reg);
 
 	if (rc < 0)
 		return rc;
 
-	val = (rc & ~bit_mask) | (val & bit_mask);
+	tmp = (rc & ~bit_mask) | (tmp & bit_mask);
 
-	return r820t_write(priv, reg, &val, 1);
+	return r820t_write(priv, reg, &tmp, 1);
 }
 
 static int r820t_read(struct r820t_priv *priv, u8 reg, u8 *val, int len)


Patches currently in stable-queue which might be from arnd@arndb.de are

queue-3.18/arm-spear600-add-missing-interrupt-parent-of-rtc.patch
queue-3.18/media-r820t-fix-r820t_write_reg-for-kasan.patch
queue-3.18/arm-spear13xx-fix-spics-gpio-controller-s-warning.patch
queue-3.18/arm-dts-s5pv210-add-interrupt-parent-for-ohci.patch
queue-3.18/arm-spear13xx-fix-dmas-cells.patch