From fdfe8d146478dccdbf355b227df5d002770f9c1b Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 30 Aug 2021 08:55:18 -0700 Subject: [PATCH] vt_kdsetmode: extend console locking BugLink: https://bugs.launchpad.net/bugs/1944610 commit 2287a51ba822384834dafc1c798453375d1107c7 upstream. As per the long-suffering comment. Reported-by: Minh Yuan Cc: Greg Kroah-Hartman Cc: Jiri Slaby Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Stefan Bader --- drivers/tty/vt/vt_ioctl.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c index af75a01ef632..7b80921e5e01 100644 --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -246,6 +246,8 @@ int vt_waitactive(int n) * * XXX It should at least call into the driver, fbdev's definitely need to * restore their engine state. --BenH + * + * Called with the console lock held. */ static int vt_kdsetmode(struct vc_data *vc, unsigned long mode) { @@ -262,7 +264,6 @@ static int vt_kdsetmode(struct vc_data *vc, unsigned long mode) return -EINVAL; } - /* FIXME: this needs the console lock extending */ if (vc->vc_mode == mode) return 0; @@ -271,12 +272,10 @@ static int vt_kdsetmode(struct vc_data *vc, unsigned long mode) return 0; /* explicitly blank/unblank the screen if switching modes */ - console_lock(); if (mode == KD_TEXT) do_unblank_screen(1); else do_blank_screen(1); - console_unlock(); return 0; } @@ -378,7 +377,10 @@ static int vt_k_ioctl(struct tty_struct *tty, unsigned int cmd, if (!perm) return -EPERM; - return vt_kdsetmode(vc, arg); + console_lock(); + ret = vt_kdsetmode(vc, arg); + console_unlock(); + return ret; case KDGETMODE: return put_user(vc->vc_mode, (int __user *)arg); -- 2.39.2