[Mesa-stable] [Mesa-dev] [PATCH] egl: Added NULL check in eglCreateContext

[Chad Versace]

On 12/08/2014 01:45 PM, Ian Romanick wrote:
> On 12/02/2014 12:10 AM, Valentin Corfu wrote:
>> With this check we can avoid segmentation fault when invalid value used during eglCreateContext.
>>
>> Cc: mesa-stable at lists.freedesktop.org
>> Cc: mesa-dev at lists.freedesktop.org
>> Signed-off-by: Valentin Corfu <valentinx.corfu at intel.com>
>> ---
>>  src/egl/drivers/dri2/egl_dri2.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
>> index d795a2f..819cb77 100644
>> --- a/src/egl/drivers/dri2/egl_dri2.c
>> +++ b/src/egl/drivers/dri2/egl_dri2.c
>> @@ -808,6 +808,11 @@ dri2_create_context(_EGLDriver *drv, _EGLDisplay *disp, _EGLConfig *conf,
>>  
>>     (void) drv;
>>  
>> +   if (conf == NULL) {
>> +      _eglError(EGL_BAD_CONFIG, "dri2_create_context");
>> +      return NULL;
>> +   }
>> +
> 
> Can't conf be NULL when used with MESA_configless_context?  See also the
> conf != NULL check at line 853.
> 
> Also, parameter validation etc. should go in eglCreateContext.

NAK. I don't know Valentin is hitting a segfault. But (conf == NULL) is
legal here. If Valentin has a backtrace, then maybe that would help us
determine a correct fix.

This same function, farther below, contains this code:

src/egl/drivers/dri2/egl_dri2.c:dri2_create_context():
    if (conf != NULL) {
        ...
    } else {
        dri_config = NULL;
    }

And as Ian points out, the config is allowed to be null if EGL_MESA_configless_context
is supported. Here's proof:
                                                                                    
EGLContext EGLAPIENTRY                                                              
eglCreateContext(EGLDisplay dpy, EGLConfig config, EGLContext share_list,           
                 const EGLint *attrib_list)                                         
{                                                                                   
   ...                              
                                                                                    
   if (!config && !disp->Extensions.MESA_configless_context)                        
      RETURN_EGL_ERROR(disp, EGL_BAD_CONFIG, EGL_NO_CONTEXT);                       
   
   ...
}                                                                                   



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