CVE-2023-54198

In the Linux kernel, the following vulnerability has been resolved:

tty: fix out-of-bounds access in tty_driver_lookup_tty()

When specifying an invalid console= device like console=tty3270,

tty_driver_lookup_tty() returns the tty struct without checking

whether index is a valid number.

To reproduce:

qemu-system-x86_64 -enable-kvm -nographic -serial mon:stdio \

-kernel ../linux-build-x86/arch/x86/boot/bzImage \

-append "console=ttyS0 console=tty3270"

This crashes with:

[ 0.770599] BUG: kernel NULL pointer dereference, address: 00000000000000ef

[ 0.771265] #PF: supervisor read access in kernel mode

[ 0.771773] #PF: error_code(0x0000) - not-present page

[ 0.772609] Oops: 0000 [#1] PREEMPT SMP PTI

[ 0.774878] RIP: 0010:tty_open+0x268/0x6f0

[ 0.784013] chrdev_open+0xbd/0x230

[ 0.784444] ? cdev_device_add+0x80/0x80

[ 0.784920] do_dentry_open+0x1e0/0x410

[ 0.785389] path_openat+0xca9/0x1050

[ 0.785813] do_filp_open+0xaa/0x150

[ 0.786240] file_open_name+0x133/0x1b0

[ 0.786746] filp_open+0x27/0x50

[ 0.787244] console_on_rootfs+0x14/0x4d

[ 0.787800] kernel_init_freeable+0x1e4/0x20d

[ 0.788383] ? rest_init+0xc0/0xc0

[ 0.788881] kernel_init+0x11/0x120

[ 0.789356] ret_from_fork+0x22/0x30