[Mesa-dev] [Mesa-stable] [PATCH 2/2] st/mesa: remove redundant stfb->iface checks

[Marek Olšák]

On Apr 25, 2017 11:23 AM, "Nicolai Hähnle" <nhaehnle at gmail.com> wrote:

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

stfb->iface is always non-NULL for an st_framebuffer. These checks
were incorrect, relying on out-of-bounds memory access in the
surface-less case of EGL_KHR_surfaceless_context.
---
 src/mesa/state_tracker/st_cb_viewport.c | 4 ++--
 src/mesa/state_tracker/st_manager.c     | 7 -------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_viewport.c
b/src/mesa/state_tracker/st_cb_viewport.c
index ff18fd0..2158c55 100644
--- a/src/mesa/state_tracker/st_cb_viewport.c
+++ b/src/mesa/state_tracker/st_cb_viewport.c
@@ -47,20 +47,20 @@ static void st_viewport(struct gl_context *ctx)
    /*
     * Normally we'd want the state tracker manager to mark the drawables
     * invalid only when needed. This will force the state tracker manager
     * to revalidate the drawable, rather than just update the context with
     * the latest cached drawable info.
     */

    stdraw = st_ws_framebuffer(st->ctx->DrawBuffer);
    stread = st_ws_framebuffer(st->ctx->ReadBuffer);

-   if (stdraw && stdraw->iface)
+   if (stdraw)
       stdraw->iface_stamp = p_atomic_read(&stdraw->iface->stamp) - 1;
-   if (stread && stread != stdraw && stread->iface)
+   if (stread && stread != stdraw && stread)


Checking stread twice? With that fixed, the series is:

Reviewed-by: Marek Olšák <marek at olsak@amd.com>


       stread->iface_stamp = p_atomic_read(&stread->iface->stamp) - 1;
 }

 void st_init_viewport_functions(struct dd_function_table *functions)
 {
    functions->Viewport = st_viewport;
 }
diff --git a/src/mesa/state_tracker/st_manager.c
b/src/mesa/state_tracker/st_manager.c
index 2ba7de6..90e4177 100644
--- a/src/mesa/state_tracker/st_manager.c
+++ b/src/mesa/state_tracker/st_manager.c
@@ -169,24 +169,20 @@ st_context_validate(struct st_context *st,
 static void
 st_framebuffer_validate(struct st_framebuffer *stfb,
                         struct st_context *st)
 {
    struct pipe_resource *textures[ST_ATTACHMENT_COUNT];
    uint width, height;
    unsigned i;
    boolean changed = FALSE;
    int32_t new_stamp;

-   /* Check for incomplete framebuffers (e.g. EGL_KHR_surfaceless_context)
*/
-   if (!stfb->iface)
-      return;
-
    new_stamp = p_atomic_read(&stfb->iface->stamp);
    if (stfb->iface_stamp == new_stamp)
       return;

    /* validate the fb */
    do {
       if (!stfb->iface->validate(&st->iface, stfb->iface, stfb->statts,
                                 stfb->num_statts, textures))
         return;

@@ -274,23 +270,20 @@ st_framebuffer_update_attachments(struct
st_framebuffer *stfb)
  * corresponds to a window and is not a user-created FBO.
  */
 static boolean
 st_framebuffer_add_renderbuffer(struct st_framebuffer *stfb,
                                 gl_buffer_index idx)
 {
    struct gl_renderbuffer *rb;
    enum pipe_format format;
    boolean sw;

-   if (!stfb->iface)
-      return FALSE;
-
    assert(_mesa_is_winsys_fbo(&stfb->Base));

    /* do not distinguish depth/stencil buffers */
    if (idx == BUFFER_STENCIL)
       idx = BUFFER_DEPTH;

    switch (idx) {
    case BUFFER_DEPTH:
       format = stfb->iface->visual->depth_stencil_format;
       sw = FALSE;
--
2.9.3

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