linux-kernel - Re: [PATCH v2] drm/amdkfd: Fix potential NULL pointer dereferences

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Date:   Thu, 11 Jan 2018 16:40:02 +0200
From:   Oded Gabbay <oded.gabbay@...il.com>
To:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Cc:     Felix Kuehling <felix.kuehling@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/amdkfd: Fix potential NULL pointer dereferences

On Thu, Jan 11, 2018 at 1:15 AM, Gustavo A. R. Silva
<garsilva@...eddedor.com> wrote:
> In case kfd_get_process_device_data returns null, there are some
> null pointer dereferences in functions kfd_bind_processes_to_device
> and kfd_unbind_processes_from_device.
>
> Fix this by printing a WARN_ON for PDDs that aren't found and skip
> them with continue statements.
>
> Addresses-Coverity-ID: 1463794 ("Dereference null return value")
> Addresses-Coverity-ID: 1463772 ("Dereference null return value")
> Suggested-by: Felix Kuehling <felix.kuehling@....com>
> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
> ---
> Changes in v2:
>  Print a WARN_ON and skip PDDs that aren't found instead of returning
>  an error.
>
>  drivers/gpu/drm/amd/amdkfd/kfd_process.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index a22fb071..4ff5f0f 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -461,7 +461,8 @@ int kfd_bind_processes_to_device(struct kfd_dev *dev)
>         hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
>                 mutex_lock(&p->mutex);
>                 pdd = kfd_get_process_device_data(dev, p);
> -               if (pdd->bound != PDD_BOUND_SUSPENDED) {
> +
> +               if (WARN_ON(!pdd) || pdd->bound != PDD_BOUND_SUSPENDED) {
>                         mutex_unlock(&p->mutex);
>                         continue;
>                 }
> @@ -501,6 +502,11 @@ void kfd_unbind_processes_from_device(struct kfd_dev *dev)
>                 mutex_lock(&p->mutex);
>                 pdd = kfd_get_process_device_data(dev, p);
>
> +               if (WARN_ON(!pdd)) {
> +                       mutex_unlock(&p->mutex);
> +                       continue;
> +               }
> +
>                 if (pdd->bound == PDD_BOUND)
>                         pdd->bound = PDD_BOUND_SUSPENDED;
>                 mutex_unlock(&p->mutex);
> --
> 2.7.4
>
This patch is:
Reviewed-by: Oded Gabbay <oded.gabbay@...il.com>