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Tetsuo Handa 58ce6d5b27 Bluetooth: defer cleanup of resources in hci_unregister_dev() 
syzbot is hitting might_sleep() warning at hci_sock_dev_event()
due to calling lock_sock() with rw spinlock held [1].

It seems that history of this locking problem is a trial and error.

Commit b40df5743e ("[PATCH] bluetooth: fix socket locking in
hci_sock_dev_event()") in 2.6.21-rc4 changed bh_lock_sock() to lock_sock()
as an attempt to fix lockdep warning.

Then, commit 4ce61d1c7a ("[BLUETOOTH]: Fix locking in
hci_sock_dev_event().") in 2.6.22-rc2 changed lock_sock() to
local_bh_disable() + bh_lock_sock_nested() as an attempt to fix
sleep in atomic context warning.

Then, commit 4b5dd696f8 ("Bluetooth: Remove local_bh_disable() from
hci_sock.c") in 3.3-rc1 removed local_bh_disable().

Then, commit e305509e67 ("Bluetooth: use correct lock to prevent UAF
of hdev object") in 5.13-rc5 again changed bh_lock_sock_nested() to
lock_sock() as an attempt to fix CVE-2021-3573.

This difficulty comes from current implementation that
hci_sock_dev_event(HCI_DEV_UNREG) is responsible for dropping all
references from sockets because hci_unregister_dev() immediately reclaims
resources as soon as returning from hci_sock_dev_event(HCI_DEV_UNREG).
But the history suggests that hci_sock_dev_event(HCI_DEV_UNREG) was not
doing what it should do.

Therefore, instead of trying to detach sockets from device, let's accept
not detaching sockets from device at hci_sock_dev_event(HCI_DEV_UNREG),
by moving actual cleanup of resources from hci_unregister_dev() to
hci_release_dev() which is called by bt_host_release when all references
to this unregistered device (which is a kobject) are gone.

Link: https://syzkaller.appspot.com/bug?extid=a5df189917e79d5e59c9 [1]
Reported-by: syzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Fixes: e305509e67 ("Bluetooth: use correct lock to prevent UAF of hdev object")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
History 2021-07-28 15:42:21 -07:00
arch ARM: dts: imx6qdl: move phy properties into phy device node 2021-07-21 14:31:22 -07:00
block block-5.14-2021-07-08 2021-07-09 12:05:33 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-07-09 11:00:44 -07:00
Documentation dt-bindings: net: fsl,fec: improve the binding a bit 2021-07-21 14:31:22 -07:00
drivers Bluetooth: btusb: Add valid le states quirk 2021-07-24 09:41:09 +02:00
fs fs: add vfs_parse_fs_param_source() helper 2021-07-14 09:19:06 -07:00
include Bluetooth: defer cleanup of resources in hci_unregister_dev() 2021-07-28 15:42:21 -07:00
init Kbuild updates for v5.14 2021-07-10 11:01:38 -07:00
ipc Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-07-15 22:40:10 -07:00
lib mm/page_alloc: Revert pahole zero-sized workaround 2021-07-10 16:09:39 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm memcg: enable accounting for IP address and routing-related objects 2021-07-20 06:00:38 -07:00
net Bluetooth: defer cleanup of resources in hci_unregister_dev() 2021-07-28 15:42:21 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-07-15 22:40:10 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-07-15 22:40:10 -07:00
security asm-generic/unaligned: Unify asm/unaligned.h around struct helper 2021-07-02 12:43:40 -07:00
sound sound fixes for 5.14-rc1 2021-07-09 11:40:26 -07:00
tools selftests: net: Test for the IOAM insertion with IPv6 2021-07-21 08:16:11 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt Merge branch 'akpm' (patches from Andrew) 2021-06-29 17:29:11 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap m68k updates for v5.14 2021-06-28 14:01:03 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: phy: add Maxlinear GPY115/21x/24x driver 2021-07-20 06:55:20 -07:00
Makefile Linux 5.14-rc1 2021-07-11 15:07:40 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.