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

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Date:   Thu, 11 Jan 2018 11:42:41 -0600
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Oded Gabbay <oded.gabbay@...il.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


Quoting Oded Gabbay <oded.gabbay@...il.com>:

> 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>

Thank you, Oded.
--
Gustavo