d1868328de
ida_alloc_range(..., min, max, ...) returns values from min to max,
inclusive.
So, NR_EXT_DEVT is a valid idx returned by blk_alloc_ext_minor().
This is an issue because in device_add_disk(), this value is used in:
ddev->devt = MKDEV(disk->major, disk->first_minor);
and NR_EXT_DEVT is '(1 << MINORBITS)'.
So, should 'disk->first_minor' be NR_EXT_DEVT, it would overflow.
Fixes: 22ae8ce8b8 ("block: simplify bdev/disk lookup in blkdev_get")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/cc17199798312406b90834e433d2cefe8266823d.1648306232.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.