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Re: [PATCH 17/22] platform/x86: alienware-wmi: fix format string overflow warning

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On Fri, Jul 14, 2017 at 3:07 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> gcc points out a possible format string overflow for a large value of 'zone':
>
> drivers/platform/x86/alienware-wmi.c: In function 'alienware_wmi_init':
> drivers/platform/x86/alienware-wmi.c:461:24: error: '%02X' directive writing between 2 and 8 bytes into a region of size 6 [-Werror=format-overflow=]
>    sprintf(buffer, "zone%02X", i);
>                         ^~~~
> drivers/platform/x86/alienware-wmi.c:461:19: note: directive argument in the range [0, 2147483646]
>    sprintf(buffer, "zone%02X", i);
>                    ^~~~~~~~~~
> drivers/platform/x86/alienware-wmi.c:461:3: note: 'sprintf' output between 7 and 13 bytes into a destination of size 10
>
> While the zone should never be that large, it's easy to make the
> buffer a few bytes longer so gcc can prove this to be safe.

Please, be a bit smarter on such fixes.

Here we need to convert

int i;

to

u8 i;

I will take it after addressing above.

P.S. You may do this change across the file.

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/platform/x86/alienware-wmi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/alienware-wmi.c b/drivers/platform/x86/alienware-wmi.c
> index 0831b428c217..acc01242da82 100644
> --- a/drivers/platform/x86/alienware-wmi.c
> +++ b/drivers/platform/x86/alienware-wmi.c
> @@ -421,7 +421,7 @@ static DEVICE_ATTR(lighting_control_state, 0644, show_control_state,
>  static int alienware_zone_init(struct platform_device *dev)
>  {
>         int i;
> -       char buffer[10];
> +       char buffer[13];
>         char *name;
>
>         if (interface == WMAX) {
> --
> 2.9.0
>



-- 
With Best Regards,
Andy Shevchenko

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[PATCH 00/22] gcc-7 -Wformat-* warnings Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:10 +0200
  [PATCH 01/22] kbuild: disable -Wformat-truncation warnings by default Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:10 +0200
  [PATCH 02/22] scsi: megaraid: fix format-overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:10 +0200
  [PATCH 07/22] scsi: gdth: increase the procfs event buffer size Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
  [PATCH 18/22] gpio: acpi: fix string overflow for large pin numbers Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 18/22] gpio: acpi: fix string overflow for large pin  numbers Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-07-14 15:00 +0200
      Re: [PATCH 18/22] gpio: acpi: fix string overflow for large pin numbers Arnd Bergmann <arnd@arndb.de> - 2017-07-14 22:00 +0200
  [PATCH 03/22] scsi: mpt3sas: fix format overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
  [PATCH 11/22] net: thunder_bgx: avoid format string overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 11/22] net: thunder_bgx: avoid format string overflow  warning Robin Murphy <robin.murphy@arm.com> - 2017-07-14 14:40 +0200
    Re: [PATCH 11/22] net: thunder_bgx: avoid format string overflow  warning David Miller <davem@davemloft.net> - 2017-07-14 18:10 +0200
  [PATCH 10/22] bnx2x: fix format overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 10/22] bnx2x: fix format overflow warning David Miller <davem@davemloft.net> - 2017-07-14 18:10 +0200
  [PATCH 21/22] fscache: fix fscache_objlist_show format processing Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
  [PATCH 14/22] [media] usbvision-i2c: fix format overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 14/22] [media] usbvision-i2c: fix format overflow warning Hans Verkuil <hverkuil@xs4all.nl> - 2017-07-17 15:00 +0200
      Re: [PATCH 14/22] [media] usbvision-i2c: fix format overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-17 15:00 +0200
        Re: [PATCH 14/22] [media] usbvision-i2c: fix format overflow warning Hans Verkuil <hverkuil@xs4all.nl> - 2017-07-17 15:00 +0200
  [PATCH 04/22] scsi: fusion: fix string overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    RE: [PATCH 04/22] scsi: fusion: fix string overflow warning David Laight <David.Laight@ACULAB.COM> - 2017-07-17 11:20 +0200
      Re: [PATCH 04/22] scsi: fusion: fix string overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-17 14:10 +0200
  [PATCH 15/22] hwmon: applesmc: fix format string overflow Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 15/22] hwmon: applesmc: fix format string overflow Guenter Roeck <linux@roeck-us.net> - 2017-07-14 16:10 +0200
  [PATCH 12/22] vmxnet3: avoid format strint overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 12/22] vmxnet3: avoid format strint overflow warning David Miller <davem@davemloft.net> - 2017-07-14 18:10 +0200
  [PATCH 17/22] platform/x86: alienware-wmi: fix format string overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    RE: [PATCH 17/22] platform/x86: alienware-wmi: fix format string  overflow warning <Mario.Limonciello@dell.com> - 2017-07-14 20:40 +0200
    Re: [PATCH 17/22] platform/x86: alienware-wmi: fix format string  overflow warning Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-14 21:20 +0200
      Re: [PATCH 17/22] platform/x86: alienware-wmi: fix format string  overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 21:40 +0200
        Re: [PATCH 17/22] platform/x86: alienware-wmi: fix format string  overflow warning Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-14 21:50 +0200
  [PATCH 05/22] scsi: gdth: avoid buffer overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
  [PATCH 09/22] net: niu: fix format string overflow warning: Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 09/22] net: niu: fix format string overflow warning: David Miller <davem@davemloft.net> - 2017-07-14 18:10 +0200
  [PATCH 08/22] isdn: divert: fix sprintf buffer overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 08/22] isdn: divert: fix sprintf buffer overflow warning David Miller <davem@davemloft.net> - 2017-07-14 18:10 +0200
  [PATCH 16/22] x86: intel-mid: fix a format string overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
  [PATCH 06/22] scsi: fnic: fix format string overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
  [PATCH 22/22] IB/mlx4: fix sprintf format warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 22/22] IB/mlx4: fix sprintf format warning Leon Romanovsky <leon@kernel.org> - 2017-07-14 15:50 +0200
  [PATCH 20/22] sound: pci: avoid string overflow warnings Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 20/22] sound: pci: avoid string overflow warnings Takashi Iwai <tiwai@suse.de> - 2017-07-14 14:30 +0200
  [PATCH 13/22] liquidio: fix possible eeprom format string overflow Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200
    Re: [PATCH 13/22] liquidio: fix possible eeprom format string  overflow David Miller <davem@davemloft.net> - 2017-07-14 18:10 +0200
  [PATCH 19/22] block: DAC960: shut up format-overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-07-14 14:20 +0200

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