[18/26,media] i2c: cx25840: avoid stack overflow with KASAN

Commit Message

Arnd Bergmann March 2, 2017, 4:38 p.m. UTC

With CONFIG_KASAN, this driver has shown a ridiculously large stack frame
in one configuration:

drivers/media/i2c/cx25840/cx25840-core.c:4960:1: error: the frame size of 94000 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

In most builds, it's only about 3300 bytes, but that's still large anough to
risk a kernel stack overflow.

Marking the two register access functions as noinline_for_kasan avoids
the problem and brings the largest stack frame size down to 232 bytes.

Signed-off-by: Arnd Bergmann <[e-mail]>
---
 drivers/media/i2c/cx25840/cx25840-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/media/i2c/cx25840/cx25840-core.c b/drivers/media/i2c/cx25840/cx25840-core.c
index b8d3c070bfc1..fd72e5a11cb9 100644
--- a/drivers/media/i2c/cx25840/cx25840-core.c
+++ b/drivers/media/i2c/cx25840/cx25840-core.c
@@ -81,7 +81,7 @@  MODULE_PARM_DESC(debug, "Debugging messages [0=Off (default) 1=On]");
 /* ----------------------------------------------------------------------- */
 static void cx23888_std_setup(struct i2c_client *client);
 
-int cx25840_write(struct i2c_client *client, u16 addr, u8 value)
+noinline_for_kasan int cx25840_write(struct i2c_client *client, u16 addr, u8 value)
 {
 	u8 buffer[3];
 	buffer[0] = addr >> 8;
@@ -90,7 +90,7 @@  int cx25840_write(struct i2c_client *client, u16 addr, u8 value)
 	return i2c_master_send(client, buffer, 3);
 }
 
-int cx25840_write4(struct i2c_client *client, u16 addr, u32 value)
+noinline_for_kasan int cx25840_write4(struct i2c_client *client, u16 addr, u32 value)
 {
 	u8 buffer[6];
 	buffer[0] = addr >> 8;