Re: [PATCH] tty: vt: selection: Add check for valid tiocl_selection values

[Jiri Slaby]

On 30. 07. 22, 20:49, Helge Deller wrote:
The line and column numbers for the selection need to start at 1.
Add the checks to prevent invalid input.
Signed-off-by: Helge Deller <del...@gmx.de>
Reported-by: syzbot+14b0e8f3fd1612e35...@syzkaller.appspotmail.com

diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index f7755e73696e..58692a9b4097 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -326,6 +326,9 @@ static int vc_selection(struct vc_data *vc, struct 
tiocl_selection *v,
                return 0;
        }

+       if (!v->xs || !v->ys || !v->xe || !v->ye)
+               return -EINVAL;

Hmm, I'm not sure about this. It potentially breaks userspace (by 
returning EINVAL now). And the code below should handle this just fine, 
right:

+
        v->xs = min_t(u16, v->xs - 1, vc->vc_cols - 1);
        v->ys = min_t(u16, v->ys - 1, vc->vc_rows - 1);
        v->xe = min_t(u16, v->xe - 1, vc->vc_cols - 1);

?

thanks,
--
js
suse labs