Re: [Xen-devel] [PATCH] console: avoid buffer overflow in guest_console_write()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.11.2019 13:01, Ian Jackson wrote:
> Jan Beulich writes ("Re: [PATCH] console: avoid buffer overflow in 
> guest_console_write()"):
>> On 29.11.2019 11:22, Andrew Cooper wrote:
>>> Is sizeof(array[0]) always 0, or is this just a GCC-ism ?  Godbolt
>>> suggests is 0 on all compiler we support.
>>>
>>> Either way, isn't the more common idiom + 0ul ?  Personally, I feel that
>>> is clearer to follow.
>>
>> I decided against + 0ul or alike because in principle size_t
>> and unsigned long are different types. In particular 32-bit
>> x86 gcc uses unsigned int for size_t, and hence min()'s
>> type safety check would cause the build to fail there. The
>> same risk obviously exists for any 32-bit arch (e.g. Arm32,
>> but I haven't checked what type it actually uses).
> 
> I don't know what i wrong with
>    (size_t)0
> which is shorter, even !

True. Yet it contains a cast, no matter how risk-free it may be
in this case. With a cast, I could as well have written (yet
shorter) (size_t)count.

Jan

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