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authorMauro Carvalho Chehab <m.chehab@samsung.com>2013-11-02 05:18:49 -0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-04 11:06:34 -0800
commit5d9befae5c21f6831ec5d7d60fc03b190156b444 (patch)
tree28e3937867a2fe9b4a02c6a6b31bcdcb4b0ee832
parent93d4a234bb94db4df2428ee44ed3a3cb524a6049 (diff)
media: stv090x: Don't use dynamic static allocation
commit f7a35df15b1f7de7823946aebc9164854e66ea07 upstream. Dynamic static allocation is evil, as Kernel stack is too low, and compilation complains about it on some archs: drivers/media/dvb-frontends/stv090x.c:750:1: warning: 'stv090x_write_regs.constprop.6' 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/stv090x.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/media/dvb-frontends/stv090x.c b/drivers/media/dvb-frontends/stv090x.c
index 56d470ad5a82..23e872f84742 100644
--- a/drivers/media/dvb-frontends/stv090x.c
+++ b/drivers/media/dvb-frontends/stv090x.c
@@ -35,6 +35,9 @@
#include "stv090x.h"
#include "stv090x_priv.h"
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE 64
+
static unsigned int verbose;
module_param(verbose, int, 0644);
@@ -722,9 +725,16 @@ static int stv090x_write_regs(struct stv090x_state *state, unsigned int reg, u8
{
const struct stv090x_config *config = state->config;
int ret;
- u8 buf[2 + count];
+ u8 buf[MAX_XFER_SIZE];
struct i2c_msg i2c_msg = { .addr = config->address, .flags = 0, .buf = buf, .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);