#2135: Segfault in map.h line 208 caused by invalid map size 0x0
------------------------------------------------+---------------------------
Reporter: corvusco...@… | Type: bug
Status: new | Priority: major
Milestone: unspecified | Component: Engine: other
Version: 2.3.4 | Keywords: segfault map
size invalid
Operating System: All/Non-Specific | Blocked By:
Blocking: |
------------------------------------------------+---------------------------
map.h line 208:
{{{
...
206 static inline unsigned char terrainType(const MAPTILE * tile)
207 {
208 return terrainTypes[TileNumber_tile(tile->texture)];
209 }
...
}}}
According to backtrace it was called from
map_Height(), map.c, line 1190
{{{
...
if (terrainType(mapTile(tileX,tileY)) == TER_WATER)
...
}}}
which in turn was called from
moveUpdateDroid(), move.c, line 3000,
the invalid tile pointer came from:
{{{
static inline WZ_DECL_PURE MAPTILE *mapTile(SDWORD x, SDWORD y)
/* Return a pointer to the tile structure at x,y */
static inline WZ_DECL_PURE MAPTILE *mapTile(SDWORD x, SDWORD y)
{
// Clamp x and y values to actual ones
// Give one tile worth of leeway before asserting, for
units/transporters coming in from off-map.
ASSERT(x >= -1, "mapTile: x value is too small (%d,%d) in
%dx%d",x,y,mapWidth,mapHeight);
ASSERT(y >= -1, "mapTile: y value is too small (%d,%d) in
%dx%d",x,y,mapWidth,mapHeight);
x = (x < 0 ? 0 : x);
y = (y < 0 ? 0 : y);
ASSERT(x < mapWidth + 1, "mapTile: x value is too big (%d,%d) in
%dx%d",x,y,mapWidth,mapHeight);
ASSERT(y < mapHeight + 1, "mapTile: y value is too big (%d,%d) in
%dx%d",x,y,mapWidth,mapHeight);
x = (x >= mapWidth ? mapWidth - 1 : x);
y = (y >= mapHeight ? mapHeight - 1 : y);
return &psMapTiles[x + (y * mapWidth)];
}
}}}
The way these checks are written, a invalid map with size mapwidth=0 and
mapheight=0 as encountered in this network game lead to the check:
{{{
x = (x >= mapWidth ? mapWidth - 1 : x);
y = (y >= mapHeight ? mapHeight - 1 : y);
}}}
calculating the pointer as
{{{
return &psMapTiles[-1];
}}}
SEGFAULT!
Though apart from the assertions handling this fatal case incorrectly, a
map with 0x0 size shouldn't have been loaded in the first place!
Please someone add a check after map download and parsing.
--
Ticket URL: <http://developer.wz2100.net/ticket/2135>
Warzone 2100 Trac <http://developer.wz2100.net/>
The Warzone 2100 Project
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