Re: [PATCH] [v4] media: s3c-camif: fix out-of-bounds array access

[Sakari Ailus <sakari.ailus@linux.intel.com>]

On Tue, Jan 16, 2018 at 10:52:15PM +0100, Arnd Bergmann wrote:
> While experimenting with older compiler versions, I ran
> into a warning that no longer shows up on gcc-4.8 or newer:
> 
> drivers/media/platform/s3c-camif/camif-capture.c: In function '__camif_subdev_try_format':
> drivers/media/platform/s3c-camif/camif-capture.c:1265:25: error: array subscript is below array bounds
> 
> This is an off-by-one bug, leading to an access before the start of the
> array, while newer compilers silently assume this undefined behavior
> cannot happen and leave the loop at index 0 if no other entry matches.
> 
> As Sylvester explains, we actually need to ensure that the
> value is within the range, so this reworks the loop to be
> easier to parse correctly, and an additional check to fall
> back on the first format value for any unexpected input.
> 
> I found an existing gcc bug for it and added a reduced version
> of the function there.
> 
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69249#c3
> Fixes: babde1c243b2 ("[media] V4L: Add driver for S3C24XX/S3C64XX SoC series camera interface")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>

-- 
Sakari Ailus
sakari.ailus@linux.intel.com