From: Eric Biggers <ebiggers@xxxxxxxxxx> commit 1aa6e058dd6cd04471b1f21298270014daf48ac9 upstream. The vc_cons_allocated() checks in vt_ioctl() and vt_compat_ioctl() are unnecessary because they can only be reached by calling ioctl() on an open tty, which implies the corresponding virtual console is allocated. And even if the virtual console *could* be freed concurrently, then these checks would be broken since they aren't done under console_lock, and the vc_data is dereferenced before them anyway. So, remove these unneeded checks to avoid confusion. Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200224080326.295046-1-ebiggers@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/vt/vt_ioctl.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -350,22 +350,13 @@ int vt_ioctl(struct tty_struct *tty, { struct vc_data *vc = tty->driver_data; struct console_font_op op; /* used in multiple places here */ - unsigned int console; + unsigned int console = vc->vc_num; unsigned char ucval; unsigned int uival; void __user *up = (void __user *)arg; int i, perm; int ret = 0; - console = vc->vc_num; - - - if (!vc_cons_allocated(console)) { /* impossible? */ - ret = -ENOIOCTLCMD; - goto out; - } - - /* * To have permissions to do most of the vt ioctls, we either have * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG. @@ -1195,14 +1186,9 @@ long vt_compat_ioctl(struct tty_struct * { struct vc_data *vc = tty->driver_data; struct console_font_op op; /* used in multiple places here */ - unsigned int console = vc->vc_num; void __user *up = compat_ptr(arg); int perm; - - if (!vc_cons_allocated(console)) /* impossible? */ - return -ENOIOCTLCMD; - /* * To have permissions to do most of the vt ioctls, we either have * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
