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Commit fa8b4729 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Sasha Levin
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media: dvb-frontends: avoid stack overflow warnings with clang 



[ Upstream commit 7a4cf27d1f0538f779bf31b8c99eda394e277119 ]

A previous patch worked around a KASAN issue in stv0367, now a similar
problem showed up with clang:

drivers/media/dvb-frontends/stv0367.c:1222:12: error: stack frame size (3624) exceeds limit (2048) in 'stv0367ter_set_frontend' [-Werror,-Wframe-larger-than]
 1214 | static int stv0367ter_set_frontend(struct dvb_frontend *fe)

Rework the stv0367_writereg() function to be simpler and mark both
register access functions as noinline_for_stack so the temporary
i2c_msg structures do not get duplicated on the stack when KASAN_STACK
is enabled.

Fixes: 3cd890db ("media: dvb-frontends: fix i2c access helpers for KASAN")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarJustin Stitt <justinstitt@google.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent d29ed089

drivers/media/dvb-frontends/stv0367.c

+8 −26
Original line number Diff line number Diff line
@@ -118,50 +118,32 @@ static const s32 stv0367cab_RF_LookUp2[RF_LOOKUP_TABLE2_SIZE][RF_LOOKUP_TABLE2_S 
	}

};



static

int stv0367_writeregs(struct stv0367_state *state, u16 reg, u8 *data, int len)

static noinline_for_stack

int stv0367_writereg(struct stv0367_state *state, u16 reg, u8 data)

{

	u8 buf[MAX_XFER_SIZE];

	u8 buf[3] = { MSB(reg), LSB(reg), data };

	struct i2c_msg msg = {

		.addr = state->config->demod_address,

		.flags = 0,

		.buf = buf,

		.len = len + 2

		.len = 3,

	};

	int ret;



	if (2 + len > sizeof(buf)) {

		printk(KERN_WARNING

		       "%s: i2c wr reg=%04x: len=%d is too big!\n",

		       KBUILD_MODNAME, reg, len);

		return -EINVAL;

	}





	buf[0] = MSB(reg);

	buf[1] = LSB(reg);

	memcpy(buf + 2, data, len);



	if (i2cdebug)

		printk(KERN_DEBUG "%s: [%02x] %02x: %02x\n", __func__,

			state->config->demod_address, reg, buf[2]);

			state->config->demod_address, reg, data);



	ret = i2c_transfer(state->i2c, &msg, 1);

	if (ret != 1)

		printk(KERN_ERR "%s: i2c write error! ([%02x] %02x: %02x)\n",

			__func__, state->config->demod_address, reg, buf[2]);

			__func__, state->config->demod_address, reg, data);



	return (ret != 1) ? -EREMOTEIO : 0;

}



static int stv0367_writereg(struct stv0367_state *state, u16 reg, u8 data)

{

	u8 tmp = data; /* see gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 */



	return stv0367_writeregs(state, reg, &tmp, 1);

}



static u8 stv0367_readreg(struct stv0367_state *state, u16 reg)

static noinline_for_stack

u8 stv0367_readreg(struct stv0367_state *state, u16 reg)

{

	u8 b0[] = { 0, 0 };

	u8 b1[] = { 0 };