From: Linus Torvalds <torvalds(a)linux-foundation.org>
stable inclusion
from linux-4.19.206
commit 0776c1a20babb4ad0b7ce7f2f4e0806a97663187
CVE: CVE-2021-3753
--------------------------------
commit 2287a51ba822384834dafc1c798453375d1107c7 upstream.
As per the long-suffering comment.
Reported-by: Minh Yuan <yuanmingbuaa(a)gmail.com>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Jiri Slaby <jirislaby(a)kernel.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang(a)huawei.com>
---
drivers/tty/vt/vt_ioctl.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 2e959563af534..13675008d1c71 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -484,16 +484,19 @@ 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
--
2.25.1