Set the terminal tilegrid NULL after free

tannewt · tannewt · commit a5520f8a3d7d · 2019-04-03T15:24:15.000-07:00
Without this, a double free can occur when a display (and terminal) is released and then a crash occurs. Upon a second release, different memory is released (sometimes the heap). When this is followed by an allocation for the flash cache, the cache can overwrite the active heap causing crashes. Fixes adafruit#1667
diff --git a/supervisor/shared/display.c b/supervisor/shared/display.c
@@ -81,6 +81,7 @@ void supervisor_start_terminal(uint16_t width_px, uint16_t height_px) {
 void supervisor_stop_terminal(void) {
     if (tilegrid_tiles != NULL) {
         free_memory(tilegrid_tiles);
+        tilegrid_tiles = NULL;
         supervisor_terminal_text_grid.inline_tiles = false;
         supervisor_terminal_text_grid.tiles = NULL;
     }

Original file line number	Diff line number	Diff line change
`@@ -81,6 +81,7 @@ void supervisor_start_terminal(uint16_t width_px, uint16_t height_px) {`
`81`	`81`	`void supervisor_stop_terminal(void) {`
`82`	`82`	`if (tilegrid_tiles != NULL) {`
`83`	`83`	`free_memory(tilegrid_tiles);`
	`84`	`+ tilegrid_tiles = NULL;`
`84`	`85`	`supervisor_terminal_text_grid.inline_tiles = false;`
`85`	`86`	`supervisor_terminal_text_grid.tiles = NULL;`
`86`	`87`	`}`