From 8393796dfa4cf5dffcceec464c7789bec3a2f471 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Sat, 2 Nov 2013 05:05:18 -0300 Subject: [media] dvb-frontends: Don't use dynamic static allocation Dynamic static allocation is evil, as Kernel stack is too low, and compilation complains about it on some archs: drivers/media/dvb-frontends/bcm3510.c:230:1: warning: 'bcm3510_do_hab_cmd' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/itd1000.c:69:1: warning: 'itd1000_write_regs.constprop.0' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/mt312.c:126:1: warning: 'mt312_write' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/nxt200x.c:111:1: warning: 'nxt200x_writebytes' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/stb6100.c:216:1: warning: 'stb6100_write_reg_range.constprop.3' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/stv6110.c:98:1: warning: 'stv6110_write_regs' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/stv6110x.c:85:1: warning: 'stv6110x_write_regs' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/tda18271c2dd.c:147:1: warning: 'WriteRegs' uses dynamic stack allocation [enabled by default] drivers/media/dvb-frontends/zl10039.c:119:1: warning: 'zl10039_write' 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 Reviewed-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-frontends/mt312.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'drivers/media/dvb-frontends/mt312.c') diff --git a/drivers/media/dvb-frontends/mt312.c b/drivers/media/dvb-frontends/mt312.c index ec388c1d6913..a74ac0ddb833 100644 --- a/drivers/media/dvb-frontends/mt312.c +++ b/drivers/media/dvb-frontends/mt312.c @@ -36,6 +36,8 @@ #include "mt312_priv.h" #include "mt312.h" +/* Max transfer size done by I2C transfer functions */ +#define MAX_XFER_SIZE 64 struct mt312_state { struct i2c_adapter *i2c; @@ -96,9 +98,15 @@ static int mt312_write(struct mt312_state *state, const enum mt312_reg_addr reg, const u8 *src, const size_t count) { int ret; - u8 buf[count + 1]; + u8 buf[MAX_XFER_SIZE]; struct i2c_msg msg; + if (1 + count > sizeof(buf)) { + printk(KERN_WARNING + "mt312: write: len=%zd is too big!\n", count); + return -EINVAL; + } + if (debug) { int i; dprintk("W(%d):", reg & 0x7f); -- cgit v1.2.3