From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 30 Aug 2021 15:55:18 +0000 (-0700)
Subject: vt_kdsetmode: extend console locking
X-Git-Tag: v4.4.283~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=01da584f08cbb1e04f22796cc49b10d570cd5ec1;p=thirdparty%2Fkernel%2Fstable.git

vt_kdsetmode: extend console locking

commit 2287a51ba822384834dafc1c798453375d1107c7 upstream.

As per the long-suffering comment.

Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index e1a8f41212063..97475bb46f84c 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -487,16 +487,19 @@ int vt_ioctl(struct tty_struct *tty,
 			ret = -EINVAL;
 			goto out;
 		}
-		/* FIXME: this needs the console lock extending */
-		if (vc->vc_mode == (unsigned char) arg)
+		console_lock();
+		if (vc->vc_mode == (unsigned char) arg) {
+			console_unlock();
 			break;
+		}
 		vc->vc_mode = (unsigned char) arg;
-		if (console != fg_console)
+		if (console != fg_console) {
+			console_unlock();
 			break;
+		}
 		/*
 		 * explicitly blank/unblank the screen if switching modes
 		 */
-		console_lock();
 		if (arg == KD_TEXT)
 			do_unblank_screen(1);
 		else