vt_ioctl: fix array_index_nospec in vt_setactivate
authorJakob Koschel <jakobkoschel@gmail.com>
Thu, 27 Jan 2022 14:44:04 +0000 (15:44 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 4 Feb 2022 14:35:53 +0000 (15:35 +0100)
commit61cc70d9e8ef5b042d4ed87994d20100ec8896d9
tree2eec697b6db573e2c49adb2d1f865e1544e3bd62
parent5d5ead5e1cafa6a6076e8c3b55f707eafc76bfbd
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: 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/20220127144406.3589293-1-jakobkoschel@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/vt/vt_ioctl.c