linux-kernel - Re: [PATCH 5.10 1/1] drm/amdkfd: Check for null pointer after calling kmemdup

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Message-ID: <CAKMK7uEgzJU8ukgR3sQtSUB5+wrD9VyMwCHOA-SReFWd0tKzzw@mail.gmail.com>
Date:   Thu, 12 Jan 2023 16:26:45 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Dragos-Marian Panait <dragos.panait@...driver.com>,
        stable@...r.kernel.org, Jiasheng Jiang <jiasheng@...as.ac.cn>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Oded Gabbay <oded.gabbay@...il.com>,
        Christian König <christian.koenig@....com>,
        Kent Russell <kent.russell@....com>,
        Harish Kasiviswanathan <Harish.Kasiviswanathan@....com>,
        dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5.10 1/1] drm/amdkfd: Check for null pointer after calling kmemdup

On Thu, 12 Jan 2023 at 13:47, Greg KH <gregkh@...uxfoundation.org> wrote:
> On Wed, Jan 04, 2023 at 07:56:33PM +0200, Dragos-Marian Panait wrote:
> > From: Jiasheng Jiang <jiasheng@...as.ac.cn>
> >
> > [ Upstream commit abfaf0eee97925905e742aa3b0b72e04a918fa9e ]
> >
> > As the possible failure of the allocation, kmemdup() may return NULL
> > pointer.
> > Therefore, it should be better to check the 'props2' in order to prevent
> > the dereference of NULL pointer.
> >
> > Fixes: 3a87177eb141 ("drm/amdkfd: Add topology support for dGPUs")
> > Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> > Reviewed-by: Felix Kuehling <Felix.Kuehling@....com>
> > Signed-off-by: Felix Kuehling <Felix.Kuehling@....com>
> > Signed-off-by: Alex Deucher <alexander.deucher@....com>
> > Signed-off-by: Dragos-Marian Panait <dragos.panait@...driver.com>
> > ---
> >  drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> > index 86b4dadf772e..02e3c650ed1c 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> > @@ -408,6 +408,9 @@ static int kfd_parse_subtype_iolink(struct crat_subtype_iolink *iolink,
> >                       return -ENODEV;
> >               /* same everything but the other direction */
> >               props2 = kmemdup(props, sizeof(*props2), GFP_KERNEL);
> > +             if (!props2)
> > +                     return -ENOMEM;
>
> Not going to queue this up as this is a bogus CVE.

Are we at the point where CVE presence actually contraindicates
backporting? At least I'm getting a bit the feeling there's a surge of
automated (security) fixes that just don't hold up to any scrutiny.
Last week I had to toss out an fbdev locking patch due to static
checker that has no clue at all how refcounting works, and so
complained that things need more locking ... (that was -fixes, but
would probably have gone to stable too if I didn't catch it).

Simple bugfixes from random people was nice when it was checkpatch
stuff and I was fairly happy to take these aggressively in drm. But my
gut feeling says things seem to be shifting towards more advanced
tooling, but without more advanced understanding by submitters. Does
that holder in other areas too?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch