From: Peter Maydell <peter.maydell@linaro.org>
To: "Andreas Färber" <afaerber@suse.de>
Cc: Riku Voipio <riku.voipio@iki.fi>, Alexander Graf <agraf@suse.de>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH] linux-user: Simplify boundary checks on g_posix_timers range
Date: Fri, 22 Aug 2014 12:45:11 +0100 [thread overview]
Message-ID: <CAFEAcA80k+TYvtFJ_wYR06KVFVa=E_=UsLGjo7i6PDUSp=3E6Q@mail.gmail.com> (raw)
In-Reply-To: <53F72B21.4010105@suse.de>
On 22 August 2014 12:36, Andreas Färber <afaerber@suse.de> wrote:
> Am 22.08.2014 13:33, schrieb Peter Maydell:
>> 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 maybe just use a local int16_t variable? I.e., should 0xffff match
> the <0 check there or not?
The kernel seems to use 'int' for the timer id type, which suggests
that this mask is just wrong.
-- PMM
next prev parent reply other threads:[~2014-08-22 11:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-22 11:19 [Qemu-devel] [PATCH] linux-user: Simplify boundary checks on g_posix_timers range Alexander Graf
2014-08-22 11:33 ` Peter Maydell
2014-08-22 11:36 ` Andreas Färber
2014-08-22 11:45 ` Peter Maydell [this message]
2014-08-22 11:42 ` Alexander Graf
2014-08-22 11:44 ` Peter Maydell
2014-08-22 11:45 ` Alexander Graf
2014-08-22 11:49 ` Peter Maydell
2014-08-22 11:52 ` Alexander Graf
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