Messages in this thread | | | Date | Sun, 31 Jul 2022 17:32:41 +0600 | Subject | Re: [PATCH] vt: Clear selection before changing the font | From | Khalid Masum <> |
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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@gmx.de>
Tested-by: Khalid Masum <khalid.masum.92@gmail.com>
> Reported-by: syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com > > 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) {
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