From: Linus Torvalds torvalds@linux-foundation.org
stable inclusion from linux-4.19.206 commit 0776c1a20babb4ad0b7ce7f2f4e0806a97663187 CVE: CVE-2021-3753
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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 Signed-off-by: Yang Yingliang yangyingliang@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