nx2: guard empty and overflowing 216 map requests, log failed whole-backing

A zero-size request at a region start wrapped last_block and wrote past the
region's blocks; the offset + size memory bounds check could overflow. Both are
guest-controlled. Also log an error when a sparse tiled image sharing the zeroed
block can't be backed whole before a GPU write.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/video_core/texture_cache/texture_cache.h b/src/video_core/texture_cache/texture_cache.h
index 5f655e5b60..33ca051482 100644
--- a/src/video_core/texture_cache/texture_cache.h
+++ b/src/video_core/texture_cache/texture_cache.h
@@ -3113,6 +3113,11 @@ void TextureCache<P>::PrepareImage(ImageId image_id, bool is_modification, bool
                 if (BackSparseTilesWhole(image)) {
                     image.dirty_ranges.clear();
                     RefreshSparseTiles(image);
+                } else {
+                    LOG_ERROR(HW_GPU,
+                              "Sparse tiled image {:#x}: out of memory backing it whole, the GPU "
+                              "write lands in the shared zeroed block",
+                              image.gpu_addr);
                 }
             }
         }