patch "vt_ioctl: change VT_RESIZEX ioctl to check for error return from" added to tty-linus

patch "vt_ioctl: change VT_RESIZEX ioctl to check for error return from" added to tty-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    vt_ioctl: change VT_RESIZEX ioctl to check for error return from

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From bc5269ca765057a1b762e79a1cfd267cd7bf1c46 Mon Sep 17 00:00:00 2001
From: George Kennedy <george.kennedy@oracle.com>
Date: Fri, 31 Jul 2020 12:33:12 -0400
Subject: vt_ioctl: change VT_RESIZEX ioctl to check for error return from
 vc_resize()

vc_resize() can return with an error after failure. Change VT_RESIZEX ioctl
to save struct vc_data values that are modified and restore the original
values in case of error.

Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Cc: stable <stable@vger.kernel.org>
Reported-by: syzbot+38a3699c7eaf165b97a6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/1596213192-6635-2-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/vt/vt_ioctl.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 91c301775047..a4e520bdd521 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -806,12 +806,22 @@ static int vt_resizex(struct vc_data *vc, struct vt_consize __user *cs)
 		console_lock();
 		vcp = vc_cons[i].d;
 		if (vcp) {
+			int ret;
+			int save_scan_lines = vcp->vc_scan_lines;
+			int save_font_height = vcp->vc_font.height;
+
 			if (v.v_vlin)
 				vcp->vc_scan_lines = v.v_vlin;
 			if (v.v_clin)
 				vcp->vc_font.height = v.v_clin;
 			vcp->vc_resize_user = 1;
-			vc_resize(vcp, v.v_cols, v.v_rows);
+			ret = vc_resize(vcp, v.v_cols, v.v_rows);
+			if (ret) {
+				vcp->vc_scan_lines = save_scan_lines;
+				vcp->vc_font.height = save_font_height;
+				console_unlock();
+				return ret;
+			}
 		}
 		console_unlock();
 	}
-- 
2.28.0