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Filename Latest commit message Latest commit date
Yufen Yu 6fcc44d1d7 block: fix use-after-free on gendisk 
commit 2da78092dd "block: Fix dev_t minor allocation lifetime"
specifically moved blk_free_devt(dev->devt) call to part_release()
to avoid reallocating device number before the device is fully
shutdown.

However, it can cause use-after-free on gendisk in get_gendisk().
We use md device as example to show the race scenes:

Process1		Worker			Process2
md_free
						blkdev_open
del_gendisk
  add delete_partition_work_fn() to wq
  						__blkdev_get
						get_gendisk
put_disk
  disk_release
    kfree(disk)
    						find part from ext_devt_idr
						get_disk_and_module(disk)
    					  	cause use after free

    			delete_partition_work_fn
			put_device(part)
    		  	part_release
		    	remove part from ext_devt_idr

Before <devt, hd_struct pointer> is removed from ext_devt_idr by
delete_partition_work_fn(), we can find the devt and then access
gendisk by hd_struct pointer. But, if we access the gendisk after
it have been freed, it can cause in use-after-freeon gendisk in
get_gendisk().

We fix this by adding a new helper blk_invalidate_devt() in
delete_partition() and del_gendisk(). It replaces hd_struct
pointer in idr with value 'NULL', and deletes the entry from
idr in part_release() as we do now.

Thanks to Jan Kara for providing the solution and more clear comments
for the code.

Fixes: 2da78092dd ("block: Fix dev_t minor allocation lifetime")
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-22 09:48:12 -06:00
arch Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
block block: fix use-after-free on gendisk 2019-04-22 09:48:12 -06:00
certs
crypto
Documentation Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
drivers Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
fs Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
include block: fix use-after-free on gendisk 2019-04-22 09:48:12 -06:00
init init: initialize jump labels before command line option parsing 2019-04-19 09:46:05 -07:00
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-04-20 10:10:49 -07:00
lib Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
LICENSES
mm Merge branch 'for-5.1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2019-04-19 15:37:22 -07:00
net NFS client bugfixes for Linux 5.1 2019-04-20 12:55:23 -07:00
samples
scripts locking/atomics: Don't assume that scripts are executable 2019-04-19 14:21:43 +02:00
security Merge branch 'for-5.1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2019-04-19 18:03:55 -07:00
sound ALSA: hda/realtek - add two more pin configuration sets to quirk table 2019-04-17 10:41:38 +02:00
tools Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS - Fix the random PID check 2019-04-20 10:43:37 -07:00
Makefile Linux 5.1-rc6 2019-04-21 10:45:57 -07:00
README

README 

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.