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Yu Kuai 64dc8c732f block, bfq: fix possible uaf for 'bfqq->bic' 
Our test report a uaf for 'bfqq->bic' in 5.10:

==================================================================
BUG: KASAN: use-after-free in bfq_select_queue+0x378/0xa30

CPU: 6 PID: 2318352 Comm: fsstress Kdump: loaded Not tainted 5.10.0-60.18.0.50.h602.kasan.eulerosv2r11.x86_64 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-20220320_160524-szxrtosci10000 04/01/2014
Call Trace:
 bfq_select_queue+0x378/0xa30
 bfq_dispatch_request+0xe8/0x130
 blk_mq_do_dispatch_sched+0x62/0xb0
 __blk_mq_sched_dispatch_requests+0x215/0x2a0
 blk_mq_sched_dispatch_requests+0x8f/0xd0
 __blk_mq_run_hw_queue+0x98/0x180
 __blk_mq_delay_run_hw_queue+0x22b/0x240
 blk_mq_run_hw_queue+0xe3/0x190
 blk_mq_sched_insert_requests+0x107/0x200
 blk_mq_flush_plug_list+0x26e/0x3c0
 blk_finish_plug+0x63/0x90
 __iomap_dio_rw+0x7b5/0x910
 iomap_dio_rw+0x36/0x80
 ext4_dio_read_iter+0x146/0x190 [ext4]
 ext4_file_read_iter+0x1e2/0x230 [ext4]
 new_sync_read+0x29f/0x400
 vfs_read+0x24e/0x2d0
 ksys_read+0xd5/0x1b0
 do_syscall_64+0x33/0x40
 entry_SYSCALL_64_after_hwframe+0x61/0xc6

Commit 3bc5e683c6 ("bfq: Split shared queues on move between cgroups")
changes that move process to a new cgroup will allocate a new bfqq to
use, however, the old bfqq and new bfqq can point to the same bic:

1) Initial state, two process with io in the same cgroup.

Process 1       Process 2
 (BIC1)          (BIC2)
  |  Λ            |  Λ
  |  |            |  |
  V  |            V  |
  bfqq1           bfqq2

2) bfqq1 is merged to bfqq2.

Process 1       Process 2
 (BIC1)          (BIC2)
  |               |
   \-------------\|
                  V
  bfqq1           bfqq2(coop)

3) Process 1 exit, then issue new io(denoce IOA) from Process 2.

 (BIC2)
  |  Λ
  |  |
  V  |
  bfqq2(coop)

4) Before IOA is completed, move Process 2 to another cgroup and issue io.

Process 2
 (BIC2)
   Λ
   |\--------------\
   |                V
  bfqq2           bfqq3

Now that BIC2 points to bfqq3, while bfqq2 and bfqq3 both point to BIC2.
If all the requests are completed, and Process 2 exit, BIC2 will be
freed while there is no guarantee that bfqq2 will be freed before BIC2.

Fix the problem by clearing bfqq->bic while bfqq is detached from bic.

Fixes: 3bc5e683c6 ("bfq: Split shared queues on move between cgroups")
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221214030430.3304151-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-14 09:50:34 -07:00
arch MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
block block, bfq: fix possible uaf for 'bfqq->bic' 2022-12-14 09:50:34 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto iov_iter work; most of that is about getting rid of 2022-12-12 18:29:54 -08:00
Documentation MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
drivers MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
fs MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
include MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
init modules changes for v6.2-rc1 2022-12-13 14:05:39 -08:00
io_uring for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
lib MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
net Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
scripts Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
security integrity-v6.2 2022-12-13 14:22:50 -08:00
sound sound updates for 6.2-rc1 2022-12-13 11:27:26 -08:00
tools MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-dwmw2-fixes' into HEAD 2022-11-23 18:59:45 -05:00
.clang-format printk changes for 6.2 2022-12-12 09:01:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: Cleanup DT Overlay intermediate files as appropriate 2022-11-18 14:45:30 -06:00
.mailmap Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MM patches for 6.2-rc1. 2022-12-13 19:29:45 -08:00
Makefile This was a not-too-busy cycle for documentation; highlights include: 2022-12-12 17:18:50 -08:00
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.