[Mesa-dev] [PATCH 10/13] mesa/main: Check context pointer in _mesa_error before using it

[Pohjolainen, Topi]

On Tue, May 05, 2015 at 02:25:26PM +0300, Juha-Pekka Heikkila wrote:
> I guess this should not really be able to segfault but still it
> seems to be able to during context creation.
> 
> Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
> ---
>  src/mesa/main/errors.c | 26 ++++++++++++++++----------
>  1 file changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/src/mesa/main/errors.c b/src/mesa/main/errors.c
> index 2aa1deb..6631b82 100644
> --- a/src/mesa/main/errors.c
> +++ b/src/mesa/main/errors.c
> @@ -1458,18 +1458,23 @@ _mesa_error( struct gl_context *ctx, GLenum error, const char *fmtString, ... )
>  
To me it looks that it would be better to just leave early already here:

      if (!ctx)
         return;

Avoids extra indentation and it doesn't look meaningful to call
should_output() with null context.

     
>     do_output = should_output(ctx, error, fmtString);
>  
> -   mtx_lock(&ctx->DebugMutex);
> -   if (ctx->Debug) {
> -      do_log = debug_is_message_enabled(ctx->Debug,
> -                                        MESA_DEBUG_SOURCE_API,
> -                                        MESA_DEBUG_TYPE_ERROR,
> -                                        error_msg_id,
> -                                        MESA_DEBUG_SEVERITY_HIGH);
> +   if (ctx) {
> +      mtx_lock(&ctx->DebugMutex);
> +      if (ctx->Debug) {
> +         do_log = debug_is_message_enabled(ctx->Debug,
> +                                           MESA_DEBUG_SOURCE_API,
> +                                           MESA_DEBUG_TYPE_ERROR,
> +                                           error_msg_id,
> +                                           MESA_DEBUG_SEVERITY_HIGH);
> +      }
> +      else {
> +         do_log = GL_FALSE;
> +      }
> +      mtx_unlock(&ctx->DebugMutex);
>     }
>     else {
>        do_log = GL_FALSE;
>     }
> -   mtx_unlock(&ctx->DebugMutex);
>  
>     if (do_output || do_log) {
>        char s[MAX_DEBUG_MESSAGE_LENGTH], s2[MAX_DEBUG_MESSAGE_LENGTH];
> @@ -1502,14 +1507,15 @@ _mesa_error( struct gl_context *ctx, GLenum error, const char *fmtString, ... )
>        }
>  
>        /* Log the error via ARB_debug_output if needed.*/
> -      if (do_log) {
> +      if (ctx && do_log) {
>           log_msg(ctx, MESA_DEBUG_SOURCE_API, MESA_DEBUG_TYPE_ERROR,
>                   error_msg_id, MESA_DEBUG_SEVERITY_HIGH, len, s2);
>        }
>     }
>  
>     /* Set the GL context error state for glGetError. */
> -   _mesa_record_error(ctx, error);
> +   if (ctx)
> +      _mesa_record_error(ctx, error);
>  }
>  
>  void
> -- 
> 1.8.5.1
> 
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