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Roman Gushchin 33391c7e1a mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() commit `3b8abb3239` upstream. KCSAN found an issue in obj_stock_flush_required(): stock->cached_objcg can be reset between the check and dereference: ================================================================== BUG: KCSAN: data-race in drain_all_stock / drain_obj_stock write to 0xffff888237c2a2f8 of 8 bytes by task 19625 on cpu 0: drain_obj_stock+0x408/0x4e0 mm/memcontrol.c:3306 refill_obj_stock+0x9c/0x1e0 mm/memcontrol.c:3340 obj_cgroup_uncharge+0xe/0x10 mm/memcontrol.c:3408 memcg_slab_free_hook mm/slab.h:587 [inline] __cache_free mm/slab.c:3373 [inline] __do_kmem_cache_free mm/slab.c:3577 [inline] kmem_cache_free+0x105/0x280 mm/slab.c:3602 __d_free fs/dcache.c:298 [inline] dentry_free fs/dcache.c:375 [inline] __dentry_kill+0x422/0x4a0 fs/dcache.c:621 dentry_kill+0x8d/0x1e0 dput+0x118/0x1f0 fs/dcache.c:913 __fput+0x3bf/0x570 fs/file_table.c:329 ____fput+0x15/0x20 fs/file_table.c:349 task_work_run+0x123/0x160 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xcf/0xe0 kernel/entry/common.c:171 exit_to_user_mode_prepare+0x6a/0xa0 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd read to 0xffff888237c2a2f8 of 8 bytes by task 19632 on cpu 1: obj_stock_flush_required mm/memcontrol.c:3319 [inline] drain_all_stock+0x174/0x2a0 mm/memcontrol.c:2361 try_charge_memcg+0x6d0/0xd10 mm/memcontrol.c:2703 try_charge mm/memcontrol.c:2837 [inline] mem_cgroup_charge_skmem+0x51/0x140 mm/memcontrol.c:7290 sock_reserve_memory+0xb1/0x390 net/core/sock.c:1025 sk_setsockopt+0x800/0x1e70 net/core/sock.c:1525 udp_lib_setsockopt+0x99/0x6c0 net/ipv4/udp.c:2692 udp_setsockopt+0x73/0xa0 net/ipv4/udp.c:2817 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3668 __sys_setsockopt+0x1c3/0x230 net/socket.c:2271 __do_sys_setsockopt net/socket.c:2282 [inline] __se_sys_setsockopt net/socket.c:2279 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2279 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0xffff8881382d52c0 -> 0xffff888138893740 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 19632 Comm: syz-executor.0 Not tainted 6.3.0-rc2-syzkaller-00387-g534293368afa #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Fix it by using READ_ONCE()/WRITE_ONCE() for all accesses to stock->cached_objcg. Link: https://lkml.kernel.org/r/20230502160839.361544-1-roman.gushchin@linux.dev Fixes: `bf4f059954` ("mm: memcg/slab: obj_cgroup API") Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Reported-by: syzbot+774c29891415ab0fd29d@syzkaller.appspotmail.com Reported-by: Dmitry Vyukov <dvyukov@google.com> Link: https://lore.kernel.org/linux-mm/CACT4Y+ZfucZhM60YPphWiCLJr6+SGFhT+jjm8k1P-a_8Kkxsjg@mail.gmail.com/T/#t Reviewed-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		History 2023-08-11 12:14:24 +02:00
arch	arm64/ptrace: Don't enable SVE when setting streaming SVE	2023-08-11 12:14:23 +02:00
block	blk-mq: Fix stall due to recursive flush plug	2023-08-03 10:25:41 +02:00
certs	KEYS: Add missing function documentation	2023-04-24 16:15:52 +03:00
crypto	crypto: jitter - correct health test during initialization	2023-07-19 16:36:19 +02:00
Documentation	Documentation: kdump: Add va_kernel_pa_offset for RISCV64	2023-08-11 12:14:19 +02:00
drivers	clk: imx93: Propagate correct error in imx93_clocks_probe()	2023-08-11 12:14:24 +02:00
fs	file: reinstate f_pos locking optimization for regular files	2023-08-11 12:14:24 +02:00
include	vxlan: Fix nexthop hash size	2023-08-11 12:14:17 +02:00
init	init, x86: Move mem_encrypt_init() into arch_cpu_finalize_init()	2023-08-08 20:04:49 +02:00
io_uring	io_uring: gate iowait schedule on having pending requests	2023-08-03 10:26:10 +02:00
ipc	Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2023-02-24 19:20:07 -08:00
kernel	bpf: Disable preemption in bpf_event_output	2023-08-11 12:14:22 +02:00
lib	lib/bitmap: workaround const_eval test build failure	2023-08-11 12:14:07 +02:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required()	2023-08-11 12:14:24 +02:00
net	libceph: fix potential hang in ceph_osdc_notify()	2023-08-11 12:14:19 +02:00
rust	rust: allocator: Prevent mis-aligned allocation	2023-08-11 12:14:18 +02:00
samples	samples: ftrace: Save required argument registers in sample trampolines	2023-07-23 13:54:09 +02:00
scripts	kbuild: rust: avoid creating temporary files	2023-07-27 08:57:06 +02:00
security	security: keys: Modify mismatched function name	2023-07-27 08:56:59 +02:00
sound	ASoC: wm8904: Fill the cache for WM8904_ADC_TEST_0 register	2023-08-03 10:26:12 +02:00
tools	test/vsock: remove vsock_perf executable on `make clean`	2023-08-11 12:14:18 +02:00
usr	initramfs: Check negative timestamp to prevent broken cpio archive	2023-04-16 17:37:01 +09:00
virt	KVM: Grab a reference to KVM for VM and vCPU stats file descriptors	2023-08-03 10:26:01 +02:00
.clang-format	cxl for v6.4	2023-04-30 11:51:51 -07:00
.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 *.dtso files	2023-02-26 15:28:23 +09:00
.gitignore	linux-kselftest-kunit-6.4-rc1	2023-04-24 12:31:32 -07:00
.mailmap	mailmap: add entries for Ben Dooks	2023-06-19 13:19:35 -07:00
.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: sctp: move Neil to CREDITS	2023-05-12 08:51:32 +01:00
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	Networking fixes for 6.4-rc8, including fixes from ipsec, bpf,	2023-06-22 17:59:51 -07:00
Makefile	Linux 6.4.9	2023-08-08 20:04:53 +02:00
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.