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Viewport: Fix use after free caused by AddChildSpriteToFoundation

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Use indices instead of pointers for last child sprite ID store

See: https://github.com/OpenTTD/OpenTTD/issues/12914
This commit is contained in:
Jonathan G Rennison 2024-08-23 17:42:42 +01:00
parent 3994f329e3
commit 4326cde313
1 changed files with 30 additions and 16 deletions
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46
src/viewport.cpp
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@ -261,12 +261,16 @@ struct BridgeSetYComparator {
}
};
using ChildStoreID = uint32_t;
static constexpr ChildStoreID NO_CHILD_STORE = UINT32_MAX;
static constexpr ChildStoreID CHILD_SPRITE_STORE_TAG = 1 << 31;
/** Data structure storing rendering information */
struct ViewportDrawer {
TunnelToMapStorage tunnel_to_map_x;
TunnelToMapStorage tunnel_to_map_y;
int *last_child;
ChildStoreID last_child;
SpriteCombineMode combine_sprites; ///< Current mode of "sprite combining". @see StartSpriteCombine
uint combine_psd_index;
@ -277,7 +281,7 @@ struct ViewportDrawer {
int foundation[FOUNDATION_PART_END]; ///< Foundation sprites (index into parent_sprites_to_draw).
FoundationPart foundation_part; ///< Currently active foundation for ground sprite drawing.
int *last_foundation_child[FOUNDATION_PART_END]; ///< Tail of ChildSprite list of the foundations. (index into child_screen_sprites_to_draw)
ChildStoreID last_foundation_child[FOUNDATION_PART_END]; ///< Tail of ChildSprite list of the foundations. (index into child_screen_sprites_to_draw)
Point foundation_offset[FOUNDATION_PART_END]; ///< Pixel offset for ground sprites on the foundations.
};
static ViewportDrawer _vd;
@ -333,6 +337,15 @@ struct ViewportDrawerDynamic {
dpi_for_text.zoom = ZOOM_LVL_MIN;
return dpi_for_text;
}
inline void SetChild(ChildStoreID store_index, int child)
{
if ((store_index & CHILD_SPRITE_STORE_TAG) != 0) {
this->child_screen_sprites_to_draw[store_index & ~CHILD_SPRITE_STORE_TAG].next = child;
} else {
this->parent_sprites_to_draw[store_index].first_child = child;
}
}
};
static void MarkRouteStepDirty(RouteStepsMap::const_iterator cit);
@ -1108,7 +1121,7 @@ static void AddChildSpriteToFoundation(SpriteID image, PaletteID pal, const SubS
Point offs = _vd.foundation_offset[foundation_part];
/* Change the active ChildSprite list to the one of the foundation */
int *old_child = _vd.last_child;
ChildStoreID old_child = _vd.last_child;
_vd.last_child = _vd.last_foundation_child[foundation_part];
AddChildSpriteScreen(image, pal, offs.x + extra_offs_x, offs.y + extra_offs_y, false, sub, false, ChildScreenSpritePositionMode::NonRelative);
@ -1178,8 +1191,8 @@ void OffsetGroundSprite(int x, int y)
default: NOT_REACHED();
}
/* _vd.last_child == nullptr if foundation sprite was clipped by the viewport bounds */
if (_vd.last_child != nullptr) _vd.foundation[_vd.foundation_part] = (uint)_vdd->parent_sprites_to_draw.size() - 1;
/* _vd.last_child == NO_CHILD_STORE if foundation sprite was clipped by the viewport bounds */
if (_vd.last_child != NO_CHILD_STORE) _vd.foundation[_vd.foundation_part] = (uint)_vdd->parent_sprites_to_draw.size() - 1;
_vd.foundation_offset[_vd.foundation_part].x = x * ZOOM_BASE;
_vd.foundation_offset[_vd.foundation_part].y = y * ZOOM_BASE;
@ -1263,7 +1276,7 @@ void AddSortableSpriteToDraw(SpriteID image, PaletteID pal, int x, int y, int w,
return;
}
_vd.last_child = nullptr;
_vd.last_child = NO_CHILD_STORE;
Point pt = RemapCoords(x, y, z);
int tmp_left, tmp_top, tmp_x = pt.x, tmp_y = pt.y;
@ -1303,6 +1316,8 @@ void AddSortableSpriteToDraw(SpriteID image, PaletteID pal, int x, int y, int w,
return;
}
_vd.last_child = static_cast<ChildStoreID>(_vdd->parent_sprites_to_draw.size());
ParentSpriteToDraw &ps = _vdd->parent_sprites_to_draw.emplace_back();
ps.x = tmp_x;
ps.y = tmp_y;
@ -1331,8 +1346,6 @@ void AddSortableSpriteToDraw(SpriteID image, PaletteID pal, int x, int y, int w,
/* bit 15 of ps.height */
// ps.comparison_done = false;
_vd.last_child = &ps.first_child;
if (_vd.combine_sprites == SPRITE_COMBINE_PENDING) {
_vd.combine_sprites = SPRITE_COMBINE_ACTIVE;
_vd.combine_psd_index = (uint)_vdd->parent_sprites_to_draw.size() - 1;
@ -1442,7 +1455,7 @@ void AddChildSpriteScreen(SpriteID image, PaletteID pal, int x, int y, bool tran
dbg_assert((image & SPRITE_MASK) < MAX_SPRITES);
/* If the ParentSprite was clipped by the viewport bounds, do not draw the ChildSprites either */
if (_vd.last_child == nullptr) return;
if (_vd.last_child == NO_CHILD_STORE) return;
/* make the sprites transparent with the right palette */
if (transparent) {
@ -1450,7 +1463,8 @@ void AddChildSpriteScreen(SpriteID image, PaletteID pal, int x, int y, bool tran
pal = PALETTE_TO_TRANSPARENT;
}
*_vd.last_child = (uint)_vdd->child_screen_sprites_to_draw.size();
_vdd->SetChild(_vd.last_child, (uint)_vdd->child_screen_sprites_to_draw.size());
const ChildStoreID child_store = static_cast<ChildStoreID>(_vdd->child_screen_sprites_to_draw.size()) | CHILD_SPRITE_STORE_TAG;
ChildScreenSpriteToDraw &cs = _vdd->child_screen_sprites_to_draw.emplace_back();
cs.image = image;
@ -1464,9 +1478,9 @@ void AddChildSpriteScreen(SpriteID image, PaletteID pal, int x, int y, bool tran
/* Append the sprite to the active ChildSprite list.
* If the active ParentSprite is a foundation, update last_foundation_child as well.
* Note: ChildSprites of foundations are NOT sequential in the vector, as selection sprites are added at last. */
if (_vd.last_foundation_child[0] == _vd.last_child) _vd.last_foundation_child[0] = &cs.next;
if (_vd.last_foundation_child[1] == _vd.last_child) _vd.last_foundation_child[1] = &cs.next;
_vd.last_child = &cs.next;
if (_vd.last_foundation_child[0] == _vd.last_child) _vd.last_foundation_child[0] = child_store;
if (_vd.last_foundation_child[1] == _vd.last_child) _vd.last_foundation_child[1] = child_store;
_vd.last_child = child_store;
}
static void AddStringToDraw(ViewportDrawerDynamic *vdd, int x, int y, StringID string, uint64_t params_1, uint64_t params_2, Colours colour, uint16_t width)
@ -1921,8 +1935,8 @@ static void ViewportAddLandscape()
_vd.foundation_part = FOUNDATION_PART_NONE;
_vd.foundation[0] = -1;
_vd.foundation[1] = -1;
_vd.last_foundation_child[0] = nullptr;
_vd.last_foundation_child[1] = nullptr;
_vd.last_foundation_child[0] = NO_CHILD_STORE;
_vd.last_foundation_child[1] = NO_CHILD_STORE;
bool no_ground_tiles = min_visible_height > 0;
_tile_type_procs[tile_type]->draw_tile_proc(&_cur_ti, { min_visible_height, no_ground_tiles });
@ -3960,7 +3974,7 @@ void ViewportDoDraw(Viewport *vp, int left, int top, int right, int bottom, uint
_vdd->dpi.left = left & mask;
_vdd->dpi.top = top & mask;
_vdd->dpi.pitch = _cur_dpi->pitch;
_vd.last_child = nullptr;
_vd.last_child = NO_CHILD_STORE;
_vdd->offset_x = UnScaleByZoomLower(_vdd->dpi.left - (vp->virtual_left & mask), vp->zoom);
_vdd->offset_y = UnScaleByZoomLower(_vdd->dpi.top - (vp->virtual_top & mask), vp->zoom);