From: Christoph Hellwig <hch@infradead.org>
To: jeffy <jeffy.chen@rock-chips.com>
Cc: Sean Paul <seanpaul@chromium.org>,
linux-kernel@vger.kernel.org, tfiga@chromium.org,
Mark Yao <mark.yao@rock-chips.com>,
Heiko Stuebner <heiko@sntech.de>,
dri-devel@lists.freedesktop.org,
linux-rockchip@lists.infradead.org,
David Airlie <airlied@linux.ie>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] drm/rockchip: Don't allow zero sized gem buffer
Date: Thu, 25 May 2017 22:52:18 -0700 [thread overview]
Message-ID: <20170526055218.GA23802@infradead.org> (raw)
In-Reply-To: <59279331.3050402@rock-chips.com>
On Fri, May 26, 2017 at 10:30:09AM +0800, jeffy wrote:
> Hi sean,
>
> On 05/25/2017 11:30 PM, Sean Paul wrote:
> > On Tue, May 23, 2017 at 02:39:43PM +0800, Jeffy Chen wrote:
> > > The system would crash when trying to alloc zero sized gem buffer:
> > > [ 6.712435] Unable to handle kernel NULL pointer dereference at virtual address 00000010 <--ZERO_SIZE_PTR
> > > ...
> > > [ 6.757502] PC is at sg_alloc_table_from_pages+0x170/0x1ec
> >
> > It's unfortunate that you didn't include the entire stack trace. From code
> > inspection, it seems like the 0 size comes from the fb_probe path? Is there
> > somewhere in the helpers that you could check the mode is sane so all drivers
> > can benefit?
>
> hmm, sorry, i was testing it on chromeos 4.4 kernel, it turns out that we
> have a custom ioctl for userspace to create gem buffer(the same as exynos
> drm), which might get the the 0 size.
>
> but on upstream kernel, it could only be called by dump_create, and the
> drm_mode_create_dumb_ioctl already did the size check.
>
> will resent this patch, and rewrite the commit message, thanx.
That suggests that this patch isn't needed at all.
next prev parent reply other threads:[~2017-05-26 5:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-23 6:39 [PATCH] drm/rockchip: Don't allow zero sized gem buffer Jeffy Chen
2017-05-25 15:30 ` Sean Paul
2017-05-26 2:30 ` jeffy
2017-05-26 5:52 ` Christoph Hellwig [this message]
2017-05-26 6:50 ` Daniel Vetter
2017-05-26 13:49 ` Sean Paul
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