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authorMauro Carvalho Chehab <m.chehab@samsung.com>2013-11-02 05:14:58 -0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-04 11:06:34 -0800
commita385eab2d1f958759f9c23923b7749b0505285f6 (patch)
tree6fda1ad6cee6c88a9f031f3330b916cacd8d38ab
parent30f028d83800c4340e0f309698465a9f364af771 (diff)
media: stb0899_drv: Don't use dynamic static allocation
commit ba4746423488aafa435739c32bfe0758f3dd5d77 upstream. Dynamic static allocation is evil, as Kernel stack is too low, and compilation complains about it on some archs: drivers/media/dvb-frontends/stb0899_drv.c:540:1: warning: 'stb0899_write_regs' uses dynamic stack allocation [enabled by default] Instead, let's enforce a limit for the buffer. Considering that I2C transfers are generally limited, and that devices used on USB has a max data length of 64 bytes for the control URBs. So, it seem safe to use 64 bytes as the hard limit for all those devices. On most cases, the limit is a way lower than that, but this limit is small enough to not affect the Kernel stack, and it is a no brain limit, as using smaller ones would require to either carefully each driver or to take a look on each datasheet. Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com> Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/media/dvb-frontends/stb0899_drv.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/media/dvb-frontends/stb0899_drv.c b/drivers/media/dvb-frontends/stb0899_drv.c
index 3dd5714eadba..07cd5ea7a038 100644
--- a/drivers/media/dvb-frontends/stb0899_drv.c
+++ b/drivers/media/dvb-frontends/stb0899_drv.c
@@ -32,6 +32,9 @@
#include "stb0899_priv.h"
#include "stb0899_reg.h"
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE 64
+
static unsigned int verbose = 0;//1;
module_param(verbose, int, 0644);
@@ -499,7 +502,7 @@ err:
int stb0899_write_regs(struct stb0899_state *state, unsigned int reg, u8 *data, u32 count)
{
int ret;
- u8 buf[2 + count];
+ u8 buf[MAX_XFER_SIZE];
struct i2c_msg i2c_msg = {
.addr = state->config->demod_address,
.flags = 0,
@@ -507,6 +510,13 @@ int stb0899_write_regs(struct stb0899_state *state, unsigned int reg, u8 *data,
.len = 2 + count
};
+ if (2 + count > sizeof(buf)) {
+ printk(KERN_WARNING
+ "%s: i2c wr reg=%04x: len=%d is too big!\n",
+ KBUILD_MODNAME, reg, count);
+ return -EINVAL;
+ }
+
buf[0] = reg >> 8;
buf[1] = reg & 0xff;
memcpy(&buf[2], data, count);