[Mesa-stable] [PATCH] st/mesa: fix memleak in glDrawPixels cache code

[Brian Paul]

If the glDrawPixels size changed, we leaked the previously cached
texture, if there was one.  This patch fixes the reference counting,
adds a refcount assertion check, and better handles potential malloc()
failures.

Tested with a modified version of the drawpix Mesa demo which changed
the image size for each glDrawPixels call.

Cc: "11.2" <mesa-stable at lists.freedesktop.org>
---
 src/mesa/state_tracker/st_cb_drawpixels.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c b/src/mesa/state_tracker/st_cb_drawpixels.c
index 01ed544..3c7bc0c 100644
--- a/src/mesa/state_tracker/st_cb_drawpixels.c
+++ b/src/mesa/state_tracker/st_cb_drawpixels.c
@@ -384,7 +384,7 @@ make_texture(struct st_context *st,
    struct gl_context *ctx = st->ctx;
    struct pipe_context *pipe = st->pipe;
    mesa_format mformat;
-   struct pipe_resource *pt;
+   struct pipe_resource *pt = NULL;
    enum pipe_format pipeFormat;
    GLenum baseInternalFormat;
 
@@ -403,10 +403,18 @@ make_texture(struct st_context *st,
        unpack->SkipRows == 0 &&
        unpack->SwapBytes == GL_FALSE &&
        st->drawpix_cache.image) {
+      assert(st->drawpix_cache.texture);
+
       /* check if the pixel data is the same */
       if (memcmp(pixels, st->drawpix_cache.image, width * height * bpp) == 0) {
          /* OK, re-use the cached texture */
-         return st->drawpix_cache.texture;
+         pipe_resource_reference(&pt, st->drawpix_cache.texture);
+         /* refcount of returned texture should be at least two here.  One
+          * reference for the cache to hold on to, one for the caller (which
+          * it will release), and possibly more held by the driver.
+          */
+         assert(pt->reference.count >= 2);
+         return pt;
       }
    }
 
@@ -525,8 +533,14 @@ make_texture(struct st_context *st,
       st->drawpix_cache.image = malloc(width * height * bpp);
       if (st->drawpix_cache.image) {
          memcpy(st->drawpix_cache.image, pixels, width * height * bpp);
+         pipe_resource_reference(&st->drawpix_cache.texture, pt);
+      }
+      else {
+         /* out of memory, free/disable cached texture */
+         st->drawpix_cache.width = 0;
+         st->drawpix_cache.height = 0;
+         pipe_resource_reference(&st->drawpix_cache.texture, NULL);
       }
-      st->drawpix_cache.texture = pt;
    }
 #endif
 
@@ -1160,9 +1174,8 @@ st_DrawPixels(struct gl_context *ctx, GLint x, GLint y,
    if (num_sampler_view > 1)
       pipe_sampler_view_reference(&sv[1], NULL);
 
-#if !USE_DRAWPIXELS_CACHE
+   /* free the texture (but may persist in the cache) */
    pipe_resource_reference(&pt, NULL);
-#endif
 }
 
 
-- 
1.9.1