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gterm: Fix allocated buffer which could be too small and result in an overflow

This commit is contained in:
mintsuki 2021-04-11 01:33:58 +02:00
parent 5434ccb598
commit 4dc24474a0
1 changed files with 21 additions and 6 deletions
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27
stage23/lib/gterm.c
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@ -31,9 +31,12 @@ static int frame_height, frame_width;
static struct image *background;
static size_t last_grid_size = 0;
static struct gterm_char *grid = NULL;
static size_t last_front_grid_size = 0;
static struct gterm_char *front_grid = NULL;
static size_t last_bg_canvas_size = 0;
static uint32_t *bg_canvas = NULL;
static bool double_buffer_enabled = false;
@ -406,10 +409,19 @@ bool gterm_init(int *_rows, int *_cols, uint32_t *_colours, int _margin, int _ma
*_cols = cols = (gterm_width - _margin * 2) / VGA_FONT_WIDTH;
*_rows = rows = (gterm_height - _margin * 2) / VGA_FONT_HEIGHT;
if (grid == NULL)
grid = ext_mem_alloc(rows * cols * sizeof(struct gterm_char));
if (front_grid == NULL)
front_grid = ext_mem_alloc(rows * cols * sizeof(struct gterm_char));
size_t new_grid_size = rows * cols * sizeof(struct gterm_char);
if (new_grid_size > last_grid_size) {
grid = ext_mem_alloc(new_grid_size);
last_grid_size = new_grid_size;
}
size_t new_front_grid_size = rows * cols * sizeof(struct gterm_char);
if (new_front_grid_size > last_front_grid_size) {
front_grid = ext_mem_alloc(new_front_grid_size);
last_front_grid_size = new_front_grid_size;
}
background = _background;
memcpy(ansi_colours, _colours, sizeof(ansi_colours));
@ -419,8 +431,11 @@ bool gterm_init(int *_rows, int *_cols, uint32_t *_colours, int _margin, int _ma
frame_height = gterm_height / 2 - (VGA_FONT_HEIGHT * rows) / 2;
frame_width = gterm_width / 2 - (VGA_FONT_WIDTH * cols) / 2;
if (bg_canvas == NULL)
bg_canvas = ext_mem_alloc(gterm_width * gterm_height * sizeof(uint32_t));
size_t new_bg_canvas_size = gterm_width * gterm_height * sizeof(uint32_t);
if (new_bg_canvas_size > last_bg_canvas_size) {
bg_canvas = ext_mem_alloc(new_bg_canvas_size);
last_bg_canvas_size = new_bg_canvas_size;
}
gterm_generate_canvas();
gterm_clear(true);