mesa: Check for framebuffer completeness before looking at the rb.

Otherwise, an incomplete framebuffer could have a NULL
_ColorReadBuffer and we'd deref that.

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

diff --git a/src/mesa/main/readpix.c b/src/mesa/main/readpix.c
index 31acfcbf13e4a1c6126406beaca83704bad11b39..1381110495f70ff3c877404b9114d34381402a31 100644 (file)
--- a/src/mesa/main/readpix.c
+++ b/src/mesa/main/readpix.c
@@ -701,6 +701,12 @@ _mesa_ReadnPixelsARB( GLint x, GLint y, GLsizei width, GLsizei height,
       return;
    }
 
+   if (ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
+      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
+                  "glReadPixels(incomplete framebuffer)" );
+      return;
+   }
+
    /* Check that the destination format and source buffer are both
     * integer-valued or both non-integer-valued.
     */
@@ -715,12 +721,6 @@ _mesa_ReadnPixelsARB( GLint x, GLint y, GLsizei width, GLsizei height,
       }
    }
 
-   if (ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
-      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
-                  "glReadPixels(incomplete framebuffer)" );
-      return;
-   }
-
    if (ctx->ReadBuffer->Name != 0 && ctx->ReadBuffer->Visual.samples > 0) {
       _mesa_error(ctx, GL_INVALID_OPERATION, "glReadPixels(multisample FBO)");
       return;