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Re: [Xen-devel] [PATCH] console: avoid buffer overflow in guest_console_write()
- To: Ian Jackson <ian.jackson@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Fri, 29 Nov 2019 12:04:30 +0000
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- Cc: Juergen Gross <jgross@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Wei Liu <wl@xxxxxxx>, Konrad Wilk <konrad.wilk@xxxxxxxxxx>, Ilja Van Sprundel <ivansprundel@xxxxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Fri, 29 Nov 2019 12:04:36 +0000
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On 29/11/2019 12:01, 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 !
Or shorter yet, (size_t)count if you're wanting to go that route.
~Andrew
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