On 7/31/22 00:50, Helge Deller wrote:
When changing the console font with ioctl(KDFONTOP) the new font size
can be bigger than the previous font. A previous selection may thus now
be outside of the new screen size and thus trigger out-of-bounds
accesses to graphics memory if the selection is removed in
vc_do_resize().
Prevent such out-of-memory accesses by dropping the selection before the
various con_font_set() console handlers are called.
Signed-off-by: Helge Deller <deller@xxxxxx>
Tested-by: Khalid Masum <khalid.masum.92@xxxxxxxxx>
Reported-by: syzbot+14b0e8f3fd1612e35350@xxxxxxxxxxxxxxxxxxxxxxxxx
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index dfc1f4b445f3..3f09205185a4 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -4662,9 +4662,11 @@ static int con_font_set(struct vc_data *vc, struct console_font_op *op)
console_lock();
if (vc->vc_mode != KD_TEXT)
rc = -EINVAL;
- else if (vc->vc_sw->con_font_set)
+ else if (vc->vc_sw->con_font_set) {
+ if (vc_is_sel(vc))
+ clear_selection();
rc = vc->vc_sw->con_font_set(vc, &font, op->flags);
- else
+ } else
rc = -ENOSYS;
console_unlock();
kfree(font.data);
@@ -4691,9 +4693,11 @@ static int con_font_default(struct vc_data *vc, struct console_font_op *op)
console_unlock();
return -EINVAL;
}
- if (vc->vc_sw->con_font_default)
+ if (vc->vc_sw->con_font_default) {
+ if (vc_is_sel(vc))
+ clear_selection();
rc = vc->vc_sw->con_font_default(vc, &font, s);
- else
+ } else
rc = -ENOSYS;
console_unlock();
if (!rc) {
