shithub: dav1d

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frame header: fix tile size parsing for non-uniform tiles

Spotted by David Michael Barr <b@rr-dav.id.au>
Fixes a fuzzing crash in crash-96e2d10fd8effbbcb0c8eedcbe05de50b1582fd2.

--- a/src/obu.c

+++ b/src/obu.c

@@ -461,8 +461,8 @@

         hdr->tiling.cols = 0;

         int widest_tile = 0, max_tile_area_sb = sbw * sbh;

         for (int sbx = 0; sbx < sbw; hdr->tiling.cols++) {

-            const int tile_w = get_uniform(gb, imin(sbw - sbx,

-                                                    max_tile_width_sb));

+            const int tile_w = 1 + get_uniform(gb, imin(sbw - sbx,

+                                                        max_tile_width_sb));

             hdr->tiling.col_start_sb[hdr->tiling.cols] = sbx;

             sbx += tile_w;

             widest_tile = imax(widest_tile, tile_w);

@@ -473,8 +473,8 @@

         hdr->tiling.rows = 0;

         for (int sby = 0; sby < sbh; hdr->tiling.rows++) {

-            const int tile_h = get_uniform(gb, imin(sbh - sby,

-                                                    max_tile_height_sb));

+            const int tile_h = 1 + get_uniform(gb, imin(sbh - sby,

+                                                        max_tile_height_sb));

             hdr->tiling.row_start_sb[hdr->tiling.rows] = sby;

             sby += tile_h;

         }