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Tetsuo Handa 6050fa4c84 loop: don't hold lo_mutex during __loop_clr_fd()
syzbot is reporting circular locking problem at __loop_clr_fd() [1], for
commit 87579e9b7d ("loop: use worker per cgroup instead of kworker")
is calling destroy_workqueue() with lo->lo_mutex held.

Since all functions where lo->lo_state matters are already checking
lo->lo_state with lo->lo_mutex held (in order to avoid racing with e.g.
ioctl(LOOP_CTL_REMOVE)), and __loop_clr_fd() can be called from either
ioctl(LOOP_CLR_FD) xor close(), lo->lo_state == Lo_rundown is considered
as an exclusive lock for __loop_clr_fd(). Therefore, hold lo->lo_mutex
inside __loop_clr_fd() only when asserting/updating lo->lo_state.

Since ioctl(LOOP_CLR_FD) depends on lo->lo_state == Lo_bound, a valid
lo->lo_backing_file must have been assigned by ioctl(LOOP_SET_FD) or
ioctl(LOOP_CONFIGURE). Thus, we can remove lo->lo_backing_file test,
and convert __loop_clr_fd() into a void function.

Link: https://syzkaller.appspot.com/bug?extid=63614029dfb79abd4383 [1]
Reported-by: syzbot <syzbot+63614029dfb79abd4383@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/8ebe3b2e-8975-7f26-0620-7144a3b8b8cd@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:47 -07:00
arch A single fix for a missing __init annotation of prepare_command_line(). 2021-11-28 09:24:50 -08:00
block block: remove the gendisk argument to blk_execute_rq 2021-11-29 06:41:29 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation block: remove blk-exec.c 2021-11-29 06:34:50 -07:00
drivers loop: don't hold lo_mutex during __loop_clr_fd() 2021-11-29 06:41:47 -07:00
fs 5 ksmbd server fixes, 4 for stable 2021-11-27 14:49:35 -08:00
include scsi: remove the gendisk argument to scsi_ioctl 2021-11-29 06:41:29 -07:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel block: remove the ->rq_disk field in struct request 2021-11-29 06:41:29 -07:00
lib parisc: Increase FRAME_WARN to 2048 bytes on parisc 2021-11-22 07:37:31 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Fixes for 5.16 folios: 2021-11-25 10:13:56 -08:00
net vhost,virtio,vdpa: bugfixes 2021-11-28 11:58:52 -08:00
samples s390 updates for 5.16-rc2 2021-11-20 10:55:50 -08:00
scripts Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2021-11-24 09:44:13 -08:00
security selinux: fix NULL-pointer dereference when hashtab allocation fails 2021-11-19 16:11:39 -05:00
sound xen: branch for v5.16-rc3 2021-11-26 09:54:13 -08:00
tools Networking fixes for 5.16-rc3, including fixes from netfilter. 2021-11-26 12:58:53 -08:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt Merge branch 'kvm-5.16-fixes' into kvm-master 2021-11-18 02:11:57 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.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 MAINTAINERS: update email address of Christian Borntraeger 2021-11-18 17:50:54 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 Networking fixes for 5.16-rc3, including fixes from netfilter. 2021-11-26 12:58:53 -08:00
Makefile Linux 5.16-rc3 2021-11-28 14:09:19 -08:00
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.