vt_ioctl: add array_index_nospec to VT_ACTIVATE

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 <[email protected]>
Signed-off-by: Brian Johannesmeyer <[email protected]>
Signed-off-by: Jakob Koschel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index e0714a9c9fd73e465263131a3e3a7286ff43bf40..58013698635f013d6ef2f1f138860ab8d82ca3db 100644 (file)
--- 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();