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Message-ID: <2e9df6e9-fa6e-46d5-b2ff-4da0efb44d74@linux.intel.com>
Date:   Mon, 30 Oct 2023 12:47:00 +0000
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Subject: Re: [PATCH v2] i915/perf: Fix NULL deref bugs with drm_dbg() calls
Content-Language: en-US
From:   Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To:     Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>,
        Matt Roper <matthew.d.roper@intel.com>,
        Lionel Landwerlin <lionel.g.landwerlin@intel.com>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Cc:     dan.carpenter@linaro.org, kernel-janitors@vger.kernel.org,
        error27@gmail.com, Tvrtko Ursulin <tvrtko.ursulin@intel.com>
References: <20231027172822.2753059-1-harshit.m.mogalapalli@oracle.com>
 <29c2bf2b-82b1-457d-ba42-29b0b30ecf32@linux.intel.com>
Organization: Intel Corporation UK Plc
In-Reply-To: <29c2bf2b-82b1-457d-ba42-29b0b30ecf32@linux.intel.com>
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On 27/10/2023 18:38, Tvrtko Ursulin wrote:
> 
> On 27/10/2023 18:28, Harshit Mogalapalli wrote:
>> When i915 perf interface is not available dereferencing it will lead to
>> NULL dereferences.
>>
>> As returning -ENOTSUPP is pretty clear return when perf interface is not
>> available.
>>
>> Fixes: 2fec539112e8 ("i915/perf: Replace DRM_DEBUG with driver 
>> specific drm_dbg call")
>> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
>> ---
>> v1 --> v2: Remove the debug calls as they don't add much value and
>> -ENOTSUPP is a good enough return value.
>> ---
>>   drivers/gpu/drm/i915/i915_perf.c | 15 +++------------
>>   1 file changed, 3 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_perf.c 
>> b/drivers/gpu/drm/i915/i915_perf.c
>> index 2f3ecd7d4804..7b1c8de2f9cb 100644
>> --- a/drivers/gpu/drm/i915/i915_perf.c
>> +++ b/drivers/gpu/drm/i915/i915_perf.c
>> @@ -4227,11 +4227,8 @@ int i915_perf_open_ioctl(struct drm_device 
>> *dev, void *data,
>>       u32 known_open_flags;
>>       int ret;
>> -    if (!perf->i915) {
>> -        drm_dbg(&perf->i915->drm,
>> -            "i915 perf interface not available for this system\n");
>> +    if (!perf->i915)
>>           return -ENOTSUPP;
>> -    }
>>       known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
>>                  I915_PERF_FLAG_FD_NONBLOCK |
>> @@ -4607,11 +4604,8 @@ int i915_perf_add_config_ioctl(struct 
>> drm_device *dev, void *data,
>>       struct i915_oa_reg *regs;
>>       int err, id;
>> -    if (!perf->i915) {
>> -        drm_dbg(&perf->i915->drm,
>> -            "i915 perf interface not available for this system\n");
>> +    if (!perf->i915)
>>           return -ENOTSUPP;
>> -    }
>>       if (!perf->metrics_kobj) {
>>           drm_dbg(&perf->i915->drm,
>> @@ -4773,11 +4767,8 @@ int i915_perf_remove_config_ioctl(struct 
>> drm_device *dev, void *data,
>>       struct i915_oa_config *oa_config;
>>       int ret;
>> -    if (!perf->i915) {
>> -        drm_dbg(&perf->i915->drm,
>> -            "i915 perf interface not available for this system\n");
>> +    if (!perf->i915)
>>           return -ENOTSUPP;
>> -    }
>>       if (i915_perf_stream_paranoid && !perfmon_capable()) {
>>           drm_dbg(&perf->i915->drm,
> 
> Thanks for re-spinning it so quickly! LGTM.
> 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Now merged to drm-intel-gt-next. Thanks again!

Regards,

Tvrtko