From: Jani Nikula <jani.nikula@linux.intel.com>
To: Daniel Vetter <daniel@ffwll.ch>, Ben Widawsky <ben@bwidawsk.net>
Cc: Intel GFX <intel-gfx@lists.freedesktop.org>,
Ben Widawsky <benjamin.widawsky@intel.com>
Subject: Re: [PATCH] drm/i915/ppgtt: Prevent NULL deref in reset ioctl
Date: Fri, 20 Dec 2013 16:37:34 +0200 [thread overview]
Message-ID: <871u17k2q9.fsf@intel.com> (raw)
In-Reply-To: <20131220141044.GA23400@phenom.ffwll.local>
On Fri, 20 Dec 2013, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Thu, Dec 19, 2013 at 10:55:56PM -0800, Ben Widawsky wrote:
>> On Fri, Dec 20, 2013 at 07:05:10AM +0100, Daniel Vetter wrote:
>> > On Fri, Dec 20, 2013 at 12:22 AM, Ben Widawsky
>> > <benjamin.widawsky@intel.com> wrote:
>> > > ctx = i915_gem_context_get(file->driver_priv, args->ctx_id);
>> > > - if (IS_ERR(ctx)) {
>> > > + if (IS_ERR_OR_NULL(ctx)) {
>> >
>> > We now have half the callers check for IS_ERR and the others not.
>> > Afaics i915_gem_context_get can only return NULL or a real context
>> > though. Also from a quite read the expected error for a lookup failure
>> > is ENOENT (and there seems to be a testcase for this).
>> > -Daniel
>>
>>
>> To your first point:
>> I think checking null is always the right thing currently, but for
>> future proofing, IS_ERR_OR_NULL is really the right thing. After his
>> patch, I believe only i915_gem_context_destroy_ioctl is still incorrect.
>
> Using IS_ERR_OR_NULL on a return value which can never contain an
> encoded errno value is imo confusing, more so when it's inconsitently
> applied.
Moreover, the error path then goes on to return 0 for success when the
pointer is NULL.
BR,
Jani.
--
Jani Nikula, Intel Open Source Technology Center
next prev parent reply other threads:[~2013-12-20 14:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-19 23:22 [PATCH] drm/i915/ppgtt: Prevent NULL deref in reset ioctl Ben Widawsky
2013-12-20 6:05 ` Daniel Vetter
2013-12-20 6:55 ` Ben Widawsky
2013-12-20 14:11 ` Daniel Vetter
2013-12-20 14:37 ` Jani Nikula [this message]
2013-12-20 18:21 ` Ben Widawsky
2013-12-20 18:21 ` Ben Widawsky
2013-12-22 20:55 ` [PATCH] drm/i915/ppgtt: Never return a NULL context Ben Widawsky
2014-01-01 5:46 ` [PATCH] [v2] " Ben Widawsky
2014-01-02 14:34 ` Mika Kuoppala
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