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Message-Id: <20180221124435.339734334@linuxfoundation.org>
Date: Wed, 21 Feb 2018 13:49:24 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Mauro Carvalho Chehab <mchehab@...pensource.com>
Subject: [PATCH 4.9 75/77] media: r820t: fix r820t_write_reg for KASAN
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Arnd Bergmann <arnd@...db.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@...db.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -396,9 +396,11 @@ 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)
@@ -411,17 +413,18 @@ 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)
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