db4df8e9d7
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 Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20221209112737.3222509-2-svens@linux.ibm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.