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

From: Helge Deller <deller@gmx.de>
To: Khalid Masum <khalid.masum.92@gmail.com>,
	syzbot <syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com>,
	dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>
Subject: [PATCH] tty: vt: selection: Add check for valid tiocl_selection values
Date: Sat, 30 Jul 2022 20:49:35 +0200	[thread overview]
Message-ID: <YuV9PybMPgc83Jis@p100> (raw)
In-Reply-To: <eb4a26aa-da30-ceee-7d27-c1e902dd4218@gmx.de>

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 <deller@gmx.de>
Reported-by: syzbot+14b0e8f3fd1612e35350@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;
+
 	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);
