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From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 22 Aug 2014 12:44:43 +0100
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Subject: Re: [Qemu-devel] [PATCH] linux-user: Simplify boundary checks on
 g_posix_timers range
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To: Alexander Graf <agraf@suse.de>
Cc: Riku Voipio <riku.voipio@iki.fi>, QEMU Developers <qemu-devel@nongnu.org>, =?UTF-8?Q?Andreas_F=C3=A4rber?= <afaerber@suse.de>

On 22 August 2014 12:42, Alexander Graf <agraf@suse.de> wrote:
> On 22.08.14 13:33, Peter Maydell wrote:
>> On 22 August 2014 12:19, Alexander Graf <agraf@suse.de> wrote:
>>> We check whether the passed in counter value is negative on all calls
>>> that involve g_posix_timers. However, we AND the value down to 16 bits
>>> right before the check, so they can never be negative.
>>
>> ...but why exactly are we doing that AND with 0xffff ?? It seems
>> unlikely that the kernel really allows random garbage in the top
>> half of the timer ID arguments, so maybe we should drop the
>> mask and keep the <0 bounds checks?
>
> Or we drop the AND and and the <0 check and treat arg1 as unsigned ;).

That probably just requires equally many changes to
code that is currently correct because the arg* are
signed but would need changes if they became unsigned.

-- PMM