vt: vt_ioctl: remove unnecessary console allocation checks

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 <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
radcolor · Apr 2, 2020 · 55280d8 · 55280d8
1 parent 94141b4
commit 55280d8
Showing 1 changed file with 2 additions and 19 deletions.
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
@@ -353,22 +353,13 @@ 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.
@@ -1208,18 +1199,10 @@ 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;
 	void __user *up = (void __user *)arg;
 	int 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.
@@ -1279,7 +1262,7 @@ long vt_compat_ioctl(struct tty_struct *tty,
 		arg = (unsigned long)compat_ptr(arg);
 		goto fallback;
 	}
-out:
+
 	return ret;
 
 fallback: