3beb8327d3
[ 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>
103 lines
2.7 KiB
C
Executable file
103 lines
2.7 KiB
C
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_NET_AFUNIX_H
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#define __LINUX_NET_AFUNIX_H
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#include <linux/socket.h>
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#include <linux/un.h>
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#include <linux/mutex.h>
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#include <linux/refcount.h>
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#include <net/sock.h>
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void unix_inflight(struct user_struct *user, struct file *fp);
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void unix_notinflight(struct user_struct *user, struct file *fp);
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void unix_destruct_scm(struct sk_buff *skb);
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void unix_gc(void);
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void wait_for_unix_gc(void);
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struct sock *unix_get_socket(struct file *filp);
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struct sock *unix_peer_get(struct sock *sk);
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#define UNIX_HASH_SIZE 256
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#define UNIX_HASH_BITS 8
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extern unsigned int unix_tot_inflight;
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extern spinlock_t unix_table_lock;
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extern struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
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struct unix_address {
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refcount_t refcnt;
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int len;
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unsigned int hash;
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struct sockaddr_un name[];
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};
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struct unix_skb_parms {
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struct pid *pid; /* Skb credentials */
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kuid_t uid;
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kgid_t gid;
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struct scm_fp_list *fp; /* Passed files */
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#ifdef CONFIG_SECURITY_NETWORK
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u32 secid; /* Security ID */
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#endif
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u32 consumed;
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} __randomize_layout;
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struct scm_stat {
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atomic_t nr_fds;
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};
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#define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb))
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/* The AF_UNIX socket */
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struct unix_sock {
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/* WARNING: sk has to be the first member */
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struct sock sk;
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struct unix_address *addr;
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struct path path;
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struct mutex iolock, bindlock;
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struct sock *peer;
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struct list_head link;
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unsigned long inflight;
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spinlock_t lock;
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unsigned long gc_flags;
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#define UNIX_GC_CANDIDATE 0
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#define UNIX_GC_MAYBE_CYCLE 1
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struct socket_wq peer_wq;
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wait_queue_entry_t peer_wake;
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struct scm_stat scm_stat;
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};
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static inline struct unix_sock *unix_sk(const struct sock *sk)
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{
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return (struct unix_sock *)sk;
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}
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#define unix_state_lock(s) spin_lock(&unix_sk(s)->lock)
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#define unix_state_unlock(s) spin_unlock(&unix_sk(s)->lock)
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enum unix_socket_lock_class {
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U_LOCK_NORMAL,
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U_LOCK_SECOND, /* for double locking, see unix_state_double_lock(). */
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U_LOCK_DIAG, /* used while dumping icons, see sk_diag_dump_icons(). */
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U_LOCK_GC_LISTENER, /* used for listening socket while determining gc
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* candidates to close a small race window.
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*/
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};
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static inline void unix_state_lock_nested(struct sock *sk,
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enum unix_socket_lock_class subclass)
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{
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spin_lock_nested(&unix_sk(sk)->lock, subclass);
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}
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#define peer_wait peer_wq.wait
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long unix_inq_len(struct sock *sk);
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long unix_outq_len(struct sock *sk);
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#ifdef CONFIG_SYSCTL
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int unix_sysctl_register(struct net *net);
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void unix_sysctl_unregister(struct net *net);
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#else
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static inline int unix_sysctl_register(struct net *net) { return 0; }
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static inline void unix_sysctl_unregister(struct net *net) {}
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#endif
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#endif
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