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vt: vt_ioctl: remove unnecessary console allocation checks 

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@google.com>
Link: https://lore.kernel.org/r/20200224080326.295046-1-ebiggers@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Biggers 2020-02-24 00:03:26 -08:00 committed by Greg Kroah-Hartman
parent c57c1644c2
commit 1aa6e058dd
1 changed files with 1 additions and 15 deletions
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16
drivers/tty/vt/vt_ioctl.c
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@ -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 *tty,
{
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.