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References: <20220227153342.79546-1-trix@redhat.com> <58ae0ccc-e964-69a3-b40b-3262fd24af9b@amd.com>
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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Mon, 28 Feb 2022 17:30:41 -0500
Message-ID: <CADnq5_Oc2mUfv41gOxrdeHjKDQ4W+S1+wiX6v_7SE6bEH-9xSA@mail.gmail.com>
Subject: Re: [PATCH v2] drm/amdgpu: Fix realloc of ptr
To:     =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Cc:     Tom Rix <trix@redhat.com>,
        "Deucher, Alexander" <alexander.deucher@amd.com>,
        xinhui pan <Xinhui.Pan@amd.com>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "Lazar, Lijo" <lijo.lazar@amd.com>,
        Nirmoy Das <nirmoy.das@amd.com>,
        Kevin Wang <kevin1.wang@amd.com>,
        Tom St Denis <tom.stdenis@amd.com>,
        "Quan, Evan" <evan.quan@amd.com>,
        Somalapuram Amaranath <Amaranath.Somalapuram@amd.com>,
        llvm@lists.linux.dev,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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Applied.  Thanks!

Alex

On Mon, Feb 28, 2022 at 5:55 AM Christian K=C3=B6nig
<christian.koenig@amd.com> wrote:
>
> Am 27.02.22 um 16:33 schrieb trix@redhat.com:
> > From: Tom Rix <trix@redhat.com>
> >
> > Clang static analysis reports this error
> > amdgpu_debugfs.c:1690:9: warning: 1st function call
> >    argument is an uninitialized value
> >    tmp =3D krealloc_array(tmp, i + 1,
> >          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > realloc uses tmp, so tmp can not be garbage.
> > And the return needs to be checked.
> >
> > Fixes: 5ce5a584cb82 ("drm/amdgpu: add debugfs for reset registers list"=
)
> > Signed-off-by: Tom Rix <trix@redhat.com>
>
> Yeah, stuff I missed because of the long review. I was already wondering
> what semantics krealloc_array is following for freeing up the pointer on
> error.
>
> Reviewed-by: Christian K=C3=B6nig <christian.koenig@amd.com>
>
> Thanks,
> Christian.
>
> > ---
> > v2:
> >    use 'new' to hold/check the ralloc return
> >    fix commit log mistake on ralloc freeing to using input ptr
> >
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 9 +++++++--
> >   1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/=
drm/amd/amdgpu/amdgpu_debugfs.c
> > index 9eb9b440bd438..2f4f8c5618d81 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> > @@ -1676,7 +1676,7 @@ static ssize_t amdgpu_reset_dump_register_list_wr=
ite(struct file *f,
> >   {
> >       struct amdgpu_device *adev =3D (struct amdgpu_device *)file_inode=
(f)->i_private;
> >       char reg_offset[11];
> > -     uint32_t *tmp;
> > +     uint32_t *new, *tmp =3D NULL;
> >       int ret, i =3D 0, len =3D 0;
> >
> >       do {
> > @@ -1687,7 +1687,12 @@ static ssize_t amdgpu_reset_dump_register_list_w=
rite(struct file *f,
> >                       goto error_free;
> >               }
> >
> > -             tmp =3D krealloc_array(tmp, i + 1, sizeof(uint32_t), GFP_=
KERNEL);
> > +             new =3D krealloc_array(tmp, i + 1, sizeof(uint32_t), GFP_=
KERNEL);
> > +             if (!new) {
> > +                     ret =3D -ENOMEM;
> > +                     goto error_free;
> > +             }
> > +             tmp =3D new;
> >               if (sscanf(reg_offset, "%X %n", &tmp[i], &ret) !=3D 1) {
> >                       ret =3D -EINVAL;
> >                       goto error_free;
>