syzbot


possible deadlock in sock_hash_update_common

Status: upstream: reported C repro on 2024/04/15 17:04
Subsystems: bpf net
[Documentation on labels]
Reported-by: syzbot+0b95946cd0588e2ad0f5@syzkaller.appspotmail.com
First crash: 40d, last: 19h21m
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bpf?] [net?] possible deadlock in sock_hash_update_common 0 (2) 2024/05/17 23:31
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in sock_hash_update_common 2 4d05h 23d 0/3 upstream: reported on 2024/04/28 11:53
Cause bisection attempts (1)
Created Duration User Patch Repo Result
2024/05/21 15:32 bisect bpf-next running

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc7-syzkaller-02064-g71ed6c266348 #0 Not tainted
------------------------------------------------------
syz-executor469/5083 is trying to acquire lock:
ffff88801ba8c2b0 (&psock->link_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88801ba8c2b0 (&psock->link_lock){+...}-{2:2}, at: sock_map_add_link net/core/sock_map.c:146 [inline]
ffff88801ba8c2b0 (&psock->link_lock){+...}-{2:2}, at: sock_hash_update_common+0x624/0xa30 net/core/sock_map.c:1041

but task is already holding lock:
ffff88801a299520 (&htab->buckets[i].lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88801a299520 (&htab->buckets[i].lock){+...}-{2:2}, at: sock_hash_update_common+0x20c/0xa30 net/core/sock_map.c:1025

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&htab->buckets[i].lock){+...}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       sock_hash_delete_elem+0x17c/0x400 net/core/sock_map.c:957
       bpf_prog_78b015942f8c5b4e+0x63/0x67
       bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline]
       __bpf_prog_run include/linux/filter.h:691 [inline]
       bpf_prog_run include/linux/filter.h:698 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2403 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2444
       trace_kfree include/trace/events/kmem.h:94 [inline]
       kfree+0x2bd/0x3b0 mm/slub.c:4383
       sk_psock_free_link include/linux/skmsg.h:425 [inline]
       sock_map_del_link net/core/sock_map.c:170 [inline]
       sock_map_unref+0x3ac/0x5e0 net/core/sock_map.c:192
       sock_map_update_common+0x4f0/0x5b0 net/core/sock_map.c:518
       sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:594
       map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1654
       __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5670
       __do_sys_bpf kernel/bpf/syscall.c:5789 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5787 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5787
       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 (&psock->link_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_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       sock_map_add_link net/core/sock_map.c:146 [inline]
       sock_hash_update_common+0x624/0xa30 net/core/sock_map.c:1041
       sock_map_update_elem_sys+0x5a4/0x910 net/core/sock_map.c:596
       map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1654
       __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5670
       __do_sys_bpf kernel/bpf/syscall.c:5789 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5787 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5787
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&htab->buckets[i].lock);
                               lock(&psock->link_lock);
                               lock(&htab->buckets[i].lock);
  lock(&psock->link_lock);

 *** DEADLOCK ***

3 locks held by syz-executor469/5083:
 #0: ffff88807e797258 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1595 [inline]
 #0: ffff88807e797258 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:129 [inline]
 #0: ffff88807e797258 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1cc/0x910 net/core/sock_map.c:590
 #1: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #1: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #1: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: sock_map_sk_acquire net/core/sock_map.c:130 [inline]
 #1: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: sock_map_update_elem_sys+0x1d8/0x910 net/core/sock_map.c:590
 #2: ffff88801a299520 (&htab->buckets[i].lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #2: ffff88801a299520 (&htab->buckets[i].lock){+...}-{2:2}, at: sock_hash_update_common+0x20c/0xa30 net/core/sock_map.c:1025

stack backtrace:
CPU: 1 PID: 5083 Comm: syz-executor469 Not tainted 6.9.0-rc7-syzkaller-02064-g71ed6c266348 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 sock_map_add_link net/core/sock_map.c:146 [inline]
 sock_hash_update_common+0x624/0xa30 net/core/sock_map.c:1041
 sock_map_update_elem_sys+0x5a4/0x910 net/core/sock_map.c:596
 map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1654
 __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5670
 __do_sys_bpf kernel/bpf/syscall.c:5789 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5787 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5787
 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
RIP: 0033:0x7f98a7323a69
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffea2336c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00

Crashes (28):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/17 23:30 bpf-next 71ed6c266348 a12e99e7 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/04/28 13:59 upstream 2c8159388952 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in sock_hash_update_common
2024/04/23 06:28 upstream 4d2008430ce8 21339d7b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in sock_hash_update_common
2024/05/09 05:43 upstream 6d7ddd805123 20bf80e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in sock_hash_update_common
2024/05/20 16:13 bpf 4b377b4868ef c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/05/19 20:10 bpf 4b377b4868ef c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/05/13 05:13 bpf 3e9bc0472b91 9026e142 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/05/06 20:48 bpf 3e9bc0472b91 c035c6de .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/05/06 05:56 bpf 3e9bc0472b91 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/05/01 21:20 bpf 3e9bc0472b91 3ba885bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/04/30 03:49 net ba1cb99b559e 27e33c58 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in sock_hash_update_common
2024/04/29 22:01 bpf b867247555c4 27e33c58 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_hash_update_common
2024/04/14 21:51 net f99c5f563c17 c8349e48 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in sock_hash_update_common
2024/05/21 08:00 bpf-next 6f130e4d4a5f c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/17 22:09 bpf-next 71ed6c266348 a12e99e7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/16 02:40 bpf-next 5c1672705a1a 0b3dad46 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/14 22:43 bpf-next 5c1672705a1a fdb4c10c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/09 22:33 bpf-next 009367099eb6 de979bc2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/07 20:23 net-next 7824463aaea9 cb2dcc0e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_hash_update_common
2024/05/05 16:16 bpf-next a9e7715ce8b3 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/05 03:57 bpf-next a9e7715ce8b3 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/04 18:59 net-next 173e7622ccb3 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_hash_update_common
2024/05/04 01:48 bpf-next a9e7715ce8b3 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/05/03 05:36 net-next dcc61472534e ddfc15a1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_hash_update_common
2024/05/02 10:52 bpf-next ac2f438c2a85 3ba885bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce possible deadlock in sock_hash_update_common
2024/04/27 20:15 linux-next bb7a2467e6be 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in sock_hash_update_common
2024/04/16 17:13 linux-next 66e4190e92ce 0d592ce4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in sock_hash_update_common
2024/04/11 16:57 linux-next 4118d9533ff3 478efa7f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in sock_hash_update_common
* Struck through repros no longer work on HEAD.