From 28cb138f559f8c1a1395f5564f86b8bbee83631b Mon Sep 17 00:00:00 2001
From: Jakob Koschel <jakobkoschel@gmail.com>
Date: Thu, 27 Jan 2022 15:44:05 +0100
Subject: [PATCH] vt_ioctl: add array_index_nospec to VT_ACTIVATE
Git-commit: 28cb138f559f8c1a1395f5564f86b8bbee83631b
Patch-mainline: v5.17-rc4
References: git-fixes

in vt_setactivate an almost identical code path has been patched
with array_index_nospec. In the VT_ACTIVATE path the user input
is from a system call argument instead of a usercopy.
For consistency both code paths should have the same mitigations
applied.

Kasper Acknowledgements: Jakob Koschel, Brian Johannesmeyer, Kaveh
Razavi, Herbert Bos, Cristiano Giuffrida from the VUSec group at VU
Amsterdam.

Co-developed-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220127144406.3589293-2-jakobkoschel@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/vt/vt_ioctl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index e0714a9c9fd7..58013698635f 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -845,6 +845,7 @@ int vt_ioctl(struct tty_struct *tty,
 			return -ENXIO;
 
 		arg--;
+		arg = array_index_nospec(arg, MAX_NR_CONSOLES);
 		console_lock();
 		ret = vc_allocate(arg);
 		console_unlock();
-- 
2.31.1