From 9d1807daefc00c7b3a4ecca02e3a783263c1e00d Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 12 Sep 2018 19:02:10 -0400
Subject: [PATCH] vt_compat_ioctl(): clean up, use compat_ptr() properly
Git-commit: 9d1807daefc00c7b3a4ecca02e3a783263c1e00d
Patch-mainline: v4.20-rc1
References: git-fixes

we need it for "convert the structure" cases too

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/vt/vt_ioctl.c | 31 +++++++++----------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index a78ad10a119b..82d38d7ba014 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -1171,17 +1171,13 @@ 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;
+	unsigned int console = vc->vc_num;
+	void __user *up = compat_ptr(arg);
 	int perm;
-	int ret = 0;
 
-	console = vc->vc_num;
 
-	if (!vc_cons_allocated(console)) { 	/* impossible? */
-		ret = -ENOIOCTLCMD;
-		goto out;
-	}
+	if (!vc_cons_allocated(console)) 	/* impossible? */
+		return -ENOIOCTLCMD;
 
 	/*
 	 * To have permissions to do most of the vt ioctls, we either have
@@ -1197,17 +1193,14 @@ long vt_compat_ioctl(struct tty_struct *tty,
 	 */
 	case PIO_FONTX:
 	case GIO_FONTX:
-		ret = compat_fontx_ioctl(cmd, up, perm, &op);
-		break;
+		return compat_fontx_ioctl(cmd, up, perm, &op);
 
 	case KDFONTOP:
-		ret = compat_kdfontop_ioctl(up, perm, &op, vc);
-		break;
+		return compat_kdfontop_ioctl(up, perm, &op, vc);
 
 	case PIO_UNIMAP:
 	case GIO_UNIMAP:
-		ret = compat_unimap_ioctl(cmd, up, perm, vc);
-		break;
+		return compat_unimap_ioctl(cmd, up, perm, vc);
 
 	/*
 	 * all these treat 'arg' as an integer
@@ -1232,21 +1225,15 @@ long vt_compat_ioctl(struct tty_struct *tty,
 	case VT_DISALLOCATE:
 	case VT_RESIZE:
 	case VT_RESIZEX:
-		goto fallback;
+		return vt_ioctl(tty, cmd, arg);
 
 	/*
 	 * the rest has a compatible data structure behind arg,
 	 * but we have to convert it to a proper 64 bit pointer.
 	 */
 	default:
-		arg = (unsigned long)compat_ptr(arg);
-		goto fallback;
+		return vt_ioctl(tty, cmd, (unsigned long)up);
 	}
-out:
-	return ret;
-
-fallback:
-	return vt_ioctl(tty, cmd, arg);
 }
 
 
-- 
2.16.4