diff options
Diffstat (limited to 'temp-6.1/af_unix-suppress-false-positive-lockdep-splat-for-sp.patch')
| -rw-r--r-- | temp-6.1/af_unix-suppress-false-positive-lockdep-splat-for-sp.patch | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/temp-6.1/af_unix-suppress-false-positive-lockdep-splat-for-sp.patch b/temp-6.1/af_unix-suppress-false-positive-lockdep-splat-for-sp.patch new file mode 100644 index 0000000000..046d5ca236 --- /dev/null +++ b/temp-6.1/af_unix-suppress-false-positive-lockdep-splat-for-sp.patch @@ -0,0 +1,171 @@ +From 32ae047c3869e6d0b5101f81baf5521a404bdd8f Mon Sep 17 00:00:00 2001 +From: Sasha Levin <sashal@kernel.org> +Date: Wed, 24 Apr 2024 10:04:43 -0700 +Subject: af_unix: Suppress false-positive lockdep splat for spin_lock() in + __unix_gc(). + +From: Kuniyuki Iwashima <kuniyu@amazon.com> + +[ Upstream commit 1971d13ffa84a551d29a81fdf5b5ec5be166ac83 ] + +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: 47d8ac011fe1 ("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> +--- + include/net/af_unix.h | 3 +++ + net/unix/garbage.c | 2 +- + 2 files changed, 4 insertions(+), 1 deletion(-) + +diff --git a/include/net/af_unix.h b/include/net/af_unix.h +index 16d6936baa2fb..e7d71a516bd4d 100644 +--- a/include/net/af_unix.h ++++ b/include/net/af_unix.h +@@ -79,6 +79,9 @@ enum unix_socket_lock_class { + U_LOCK_NORMAL, + U_LOCK_SECOND, /* for double locking, see unix_state_double_lock(). */ + U_LOCK_DIAG, /* used while dumping icons, see sk_diag_dump_icons(). */ ++ U_LOCK_GC_LISTENER, /* used for listening socket while determining gc ++ * candidates to close a small race window. ++ */ + }; + + static inline void unix_state_lock_nested(struct sock *sk, +diff --git a/net/unix/garbage.c b/net/unix/garbage.c +index 85c6f05c0fa3c..d2fc795394a52 100644 +--- a/net/unix/garbage.c ++++ b/net/unix/garbage.c +@@ -260,7 +260,7 @@ void unix_gc(void) + __set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags); + + if (sk->sk_state == TCP_LISTEN) { +- unix_state_lock(sk); ++ unix_state_lock_nested(sk, U_LOCK_GC_LISTENER); + unix_state_unlock(sk); + } + } +-- +2.43.0 + |