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Kuniyuki Iwashima 753a277ea0 af_unix: Suppress false-positive lockdep splat for spin_lock() in __unix_gc(). [ Upstream commit `1971d13ffa` ] syzbot reported a lockdep splat regarding unix_gc_lock and unix_state_lock(). One is called from recvmsg() for a connected socket, and another is called from GC for TCP_LISTEN socket. So, the splat is false-positive. Let's add a dedicated lock class for the latter to suppress the splat. Note that this change is not necessary for net-next.git as the issue is only applied to the old GC impl. [0]: WARNING: possible circular locking dependency detected 6.9.0-rc5-syzkaller-00007-g4d2008430ce8 #0 Not tainted ----------------------------------------------------- kworker/u8:1/11 is trying to acquire lock: ffff88807cea4e70 (&u->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88807cea4e70 (&u->lock){+.+.}-{2:2}, at: __unix_gc+0x40e/0xf70 net/unix/garbage.c:302 but task is already holding lock: ffffffff8f6ab638 (unix_gc_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffffffff8f6ab638 (unix_gc_lock){+.+.}-{2:2}, at: __unix_gc+0x117/0xf70 net/unix/garbage.c:261 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (unix_gc_lock){+.+.}-{2:2}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] unix_notinflight+0x13d/0x390 net/unix/garbage.c:140 unix_detach_fds net/unix/af_unix.c:1819 [inline] unix_destruct_scm+0x221/0x350 net/unix/af_unix.c:1876 skb_release_head_state+0x100/0x250 net/core/skbuff.c:1188 skb_release_all net/core/skbuff.c:1200 [inline] __kfree_skb net/core/skbuff.c:1216 [inline] kfree_skb_reason+0x16d/0x3b0 net/core/skbuff.c:1252 kfree_skb include/linux/skbuff.h:1262 [inline] manage_oob net/unix/af_unix.c:2672 [inline] unix_stream_read_generic+0x1125/0x2700 net/unix/af_unix.c:2749 unix_stream_splice_read+0x239/0x320 net/unix/af_unix.c:2981 do_splice_read fs/splice.c:985 [inline] splice_file_to_pipe+0x299/0x500 fs/splice.c:1295 do_splice+0xf2d/0x1880 fs/splice.c:1379 __do_splice fs/splice.c:1436 [inline] __do_sys_splice fs/splice.c:1652 [inline] __se_sys_splice+0x331/0x4a0 fs/splice.c:1634 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&u->lock){+.+.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __unix_gc+0x40e/0xf70 net/unix/garbage.c:302 process_one_work kernel/workqueue.c:3254 [inline] process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(unix_gc_lock); lock(&u->lock); lock(unix_gc_lock); lock(&u->lock); * DEADLOCK * 3 locks held by kworker/u8:1/11: #0: ffff888015089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline] #0: ffff888015089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x17c0 kernel/workqueue.c:3335 #1: ffffc90000107d00 (unix_gc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline] #1: ffffc90000107d00 (unix_gc_work){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x17c0 kernel/workqueue.c:3335 #2: ffffffff8f6ab638 (unix_gc_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #2: ffffffff8f6ab638 (unix_gc_lock){+.+.}-{2:2}, at: __unix_gc+0x117/0xf70 net/unix/garbage.c:261 stack backtrace: CPU: 0 PID: 11 Comm: kworker/u8:1 Not tainted 6.9.0-rc5-syzkaller-00007-g4d2008430ce8 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Workqueue: events_unbound __unix_gc Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __unix_gc+0x40e/0xf70 net/unix/garbage.c:302 process_one_work kernel/workqueue.c:3254 [inline] process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Fixes: `47d8ac011f` ("af_unix: Fix garbage collector racing against connect()") Reported-and-tested-by: syzbot+fa379358c28cc87cc307@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fa379358c28cc87cc307 Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20240424170443.9832-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		History 2024-05-02 16:32:40 +02:00
arch	ARM: dts: imx6ull-tarragon: fix USB over-current polarity	2024-05-02 16:32:39 +02:00
block	block: fix q->blkg_list corruption during disk rebind	2024-04-17 11:19:28 +02:00
certs	certs: Reference revocation list for all keyrings	2023-08-17 20:12:41 +00:00
crypto	crypto: jitter - fix CRYPTO_JITTERENTROPY help text	2024-03-26 18:19:52 -04:00
Documentation	net: make SK_MEMORY_PCPU_RESERV tunable	2024-05-02 16:32:36 +02:00
drivers	net: ethernet: ti: am65-cpts: Fix PTPv1 message type on TX packets	2024-05-02 16:32:40 +02:00
fs	cifs: reinstate original behavior again for forceuid/forcegid	2024-05-02 16:32:30 +02:00
include	af_unix: Suppress false-positive lockdep splat for spin_lock() in __unix_gc().	2024-05-02 16:32:40 +02:00
init	init/main.c: Fix potential static_command_line memory overflow	2024-04-27 17:11:41 +02:00
io_uring	io_uring: Fix io_cqring_wait() not restoring sigmask on get_timespec64() failure	2024-04-27 17:11:30 +02:00
ipc	Add x86 shadow stack support	2023-08-31 12:20:12 -07:00
kernel	sched: Add missing memory barrier in switch_mm_cid	2024-04-27 17:11:41 +02:00
lib	bootconfig: use memblock_free_late to free xbc memory to buddy	2024-04-27 17:11:43 +02:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm/shmem: inline shmem_is_huge() for disabled transparent hugepages	2024-04-27 17:11:42 +02:00
net	af_unix: Suppress false-positive lockdep splat for spin_lock() in __unix_gc().	2024-05-02 16:32:40 +02:00
rust	rust: upgrade to Rust 1.73.0	2024-02-16 19:10:43 +01:00
samples	work around gcc bugs with 'asm goto' with outputs	2024-02-23 09:24:47 +01:00
scripts	gcc-plugins/stackleak: Avoid .head.text section	2024-04-13 13:07:40 +02:00
security	selinux: avoid dereference of garbage after mount failure	2024-04-10 16:35:48 +02:00
sound	ALSA: hda/realtek - Enable audio jacks of Haier Boyue G42 with ALC269VC	2024-04-27 17:11:38 +02:00
tools	tools: ynl: don't ignore errors in NLMSG_DONE messages	2024-05-02 16:32:36 +02:00
usr	initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP	2023-06-06 17:54:49 +09:00
virt	KVM: Always flush async #PF workqueue when vCPU is being destroyed	2024-04-03 15:28:18 +02:00
.clang-format	iommu: Add for_each_group_device()	2023-05-23 08:15:51 +02:00
.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: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	kbuild: rpm-pkg: rename binkernel.spec to kernel.spec	2023-07-25 00:59:33 +09:00
.mailmap	20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues	2023-10-24 09:52:16 -10:00
.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	USB: Remove Wireless USB and UWB documentation	2023-08-09 14:17:32 +02:00
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	ALSA: scarlett2: Rename scarlett_gen2 to scarlett2	2024-04-27 17:11:36 +02:00
Makefile	Linux 6.6.29	2024-04-27 17:11:44 +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.