From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: "Guido Günther" <agx@sigxcpu.org>
Cc: Arnd Bergmann <arnd@arndb.de>, David Airlie <airlied@linux.ie>,
etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
linux-kernel@vger.kernel.org,
Emil Velikov <emil.velikov@collabora.com>,
Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH] drm/etnaviv: only reject timeouts with tv_nsec >= 2 seconds
Date: Tue, 21 Jan 2020 13:02:42 +0000 [thread overview]
Message-ID: <20200121130241.GG25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20200121125546.GA71415@bogon.m.sigxcpu.org>
On Tue, Jan 21, 2020 at 01:55:46PM +0100, Guido Günther wrote:
> Hi,
> On Tue, Jan 21, 2020 at 12:45:25PM +0100, Arnd Bergmann wrote:
> > As Guido Günther reported, get_abs_timeout() in the etnaviv user space
> > sometimes passes timeouts with nanosecond values larger than 1000000000,
> > which gets rejected after my first patch.
> >
> > To avoid breaking this, while also not allowing completely arbitrary
> > values, set the limit to 1999999999 and use set_normalized_timespec64()
> > to get the correct format before comparing it.
>
> I'm seeing values up to 5 seconds so I need
>
> if (args->timeout.tv_nsec > (5 * NSEC_PER_SEC))
I assume you're looking at 64-bit, but I suspect userspace needs
looking at considering 32-bit. If userspace uses a 32-bit tv_nsec
anywhere in the path that it attempts to pass up to 5 seconds in
tv_nsec, then this will fail to pass the correct timeout.
If that is the case, userspace is buggy, and needs fixing not to
pass such large values through tv_nsec irrespective of this issue.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
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WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: "Guido Günther" <agx@sigxcpu.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Lucas Stach <l.stach@pengutronix.de>,
Christian Gmeiner <christian.gmeiner@gmail.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Philipp Zabel <p.zabel@pengutronix.de>,
Sam Ravnborg <sam@ravnborg.org>, Rob Herring <robh@kernel.org>,
Emil Velikov <emil.velikov@collabora.com>,
etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/etnaviv: only reject timeouts with tv_nsec >= 2 seconds
Date: Tue, 21 Jan 2020 13:02:42 +0000 [thread overview]
Message-ID: <20200121130241.GG25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20200121125546.GA71415@bogon.m.sigxcpu.org>
On Tue, Jan 21, 2020 at 01:55:46PM +0100, Guido Günther wrote:
> Hi,
> On Tue, Jan 21, 2020 at 12:45:25PM +0100, Arnd Bergmann wrote:
> > As Guido Günther reported, get_abs_timeout() in the etnaviv user space
> > sometimes passes timeouts with nanosecond values larger than 1000000000,
> > which gets rejected after my first patch.
> >
> > To avoid breaking this, while also not allowing completely arbitrary
> > values, set the limit to 1999999999 and use set_normalized_timespec64()
> > to get the correct format before comparing it.
>
> I'm seeing values up to 5 seconds so I need
>
> if (args->timeout.tv_nsec > (5 * NSEC_PER_SEC))
I assume you're looking at 64-bit, but I suspect userspace needs
looking at considering 32-bit. If userspace uses a 32-bit tv_nsec
anywhere in the path that it attempts to pass up to 5 seconds in
tv_nsec, then this will fail to pass the correct timeout.
If that is the case, userspace is buggy, and needs fixing not to
pass such large values through tv_nsec irrespective of this issue.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
next prev parent reply other threads:[~2020-01-21 13:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 11:45 [PATCH] drm/etnaviv: only reject timeouts with tv_nsec >= 2 seconds Arnd Bergmann
2020-01-21 11:45 ` Arnd Bergmann
2020-01-21 12:55 ` Guido Günther
2020-01-21 12:55 ` Guido Günther
2020-01-21 13:02 ` Russell King - ARM Linux admin [this message]
2020-01-21 13:02 ` Russell King - ARM Linux admin
2020-01-21 16:09 ` Lucas Stach
2020-01-21 16:09 ` Lucas Stach
2020-01-21 19:05 ` Arnd Bergmann
2020-01-21 19:05 ` Arnd Bergmann
2020-01-22 10:30 ` Guido Günther
2020-01-22 10:30 ` Guido Günther
2020-01-22 10:35 ` Russell King - ARM Linux admin
2020-01-22 10:35 ` Russell King - ARM Linux admin
2020-01-24 8:56 ` Guido Günther
2020-01-24 8:56 ` Guido Günther
2020-01-28 13:07 ` Arnd Bergmann
2020-01-28 13:07 ` Arnd Bergmann
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