On Tue 2020-09-01 17:10:40, Greg Kroah-Hartman wrote:
From: George Kennedy george.kennedy@oracle.com
commit 39b3cffb8cf3111738ea993e2757ab382253d86a upstream.
Add a check to fbcon_resize() to ensure that a possible change to user font height or user font width will not allow a font data out-of-bounds access. NOTE: must use original charcount in calculation as font charcount can change and cannot be used to determine the font data allocated size.
+#define PITCH(w) (((w) + 7) >> 3) +#define CALC_FONTSZ(h, p, c) ((h) * (p) * (c)) /* size = height * pitch * charcount */
Ok, so we validate data from user. Can this overflow? Should it be inline function for readability?
static int fbcon_resize(struct vc_data *vc, unsigned int width, unsigned int height, unsigned int user) { @@ -2161,6 +2164,24 @@ static int fbcon_resize(struct vc_data * struct fb_var_screeninfo var = info->var; int x_diff, y_diff, virt_w, virt_h, virt_fw, virt_fh;
- if (ops->p && ops->p->userfont && FNTSIZE(vc->vc_font.data)) {
int size;int pitch = PITCH(vc->vc_font.width);
Should size be unsigned?
Best regards, Pavel