Commit 61cc70d9 authored by Jakob Koschel's avatar Jakob Koschel Committed by Greg Kroah-Hartman
Browse files

vt_ioctl: fix array_index_nospec in vt_setactivate 



array_index_nospec ensures that an out-of-bounds value is set to zero
on the transient path. Decreasing the value by one afterwards causes
a transient integer underflow. vsa.console should be decreased first
and then sanitized with array_index_nospec.

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

Co-developed-by: default avatarBrian Johannesmeyer <bjohannesmeyer@gmail.com>
Signed-off-by: default avatarBrian Johannesmeyer <bjohannesmeyer@gmail.com>
Signed-off-by: default avatarJakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220127144406.3589293-1-jakobkoschel@gmail.com


Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5d5ead5e

drivers/tty/vt/vt_ioctl.c

+1 −1
Original line number Diff line number Diff line
@@ -599,8 +599,8 @@ static int vt_setactivate(struct vt_setactivate __user *sa) 
	if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)

		return -ENXIO;



	vsa.console = array_index_nospec(vsa.console, MAX_NR_CONSOLES + 1);

	vsa.console--;

	vsa.console = array_index_nospec(vsa.console, MAX_NR_CONSOLES);

	console_lock();

	ret = vc_allocate(vsa.console);

	if (ret) {