====================================================== WARNING: possible circular locking dependency detected 4.14.291-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/10275 is trying to acquire lock: ((&strp->work)){+.+.}, at: [] flush_work+0x88/0x770 kernel/workqueue.c:2887 but task is already holding lock: (sk_lock-AF_INET){+.+.}, at: [] lock_sock include/net/sock.h:1473 [inline] (sk_lock-AF_INET){+.+.}, at: [] kcm_attach net/kcm/kcmsock.c:1390 [inline] (sk_lock-AF_INET){+.+.}, at: [] kcm_attach_ioctl net/kcm/kcmsock.c:1490 [inline] (sk_lock-AF_INET){+.+.}, at: [] kcm_ioctl+0x328/0xfb0 net/kcm/kcmsock.c:1701 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_INET){+.+.}: lock_sock_nested+0xb7/0x100 net/core/sock.c:2813 do_strp_work net/strparser/strparser.c:415 [inline] strp_work+0x3e/0x100 net/strparser/strparser.c:434 process_one_work+0x793/0x14a0 kernel/workqueue.c:2117 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 -> #0 ((&strp->work)){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 flush_work+0xad/0x770 kernel/workqueue.c:2890 __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965 strp_done+0x53/0xd0 net/strparser/strparser.c:519 kcm_attach net/kcm/kcmsock.c:1429 [inline] kcm_attach_ioctl net/kcm/kcmsock.c:1490 [inline] kcm_ioctl+0x828/0xfb0 net/kcm/kcmsock.c:1701 sock_do_ioctl net/socket.c:974 [inline] sock_ioctl+0x2cc/0x4c0 net/socket.c:1071 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_INET); lock((&strp->work)); lock(sk_lock-AF_INET); lock((&strp->work)); *** DEADLOCK *** 1 lock held by syz-executor.0/10275: #0: (sk_lock-AF_INET){+.+.}, at: [] lock_sock include/net/sock.h:1473 [inline] #0: (sk_lock-AF_INET){+.+.}, at: [] kcm_attach net/kcm/kcmsock.c:1390 [inline] #0: (sk_lock-AF_INET){+.+.}, at: [] kcm_attach_ioctl net/kcm/kcmsock.c:1490 [inline] #0: (sk_lock-AF_INET){+.+.}, at: [] kcm_ioctl+0x328/0xfb0 net/kcm/kcmsock.c:1701 stack backtrace: CPU: 1 PID: 10275 Comm: syz-executor.0 Not tainted 4.14.291-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 flush_work+0xad/0x770 kernel/workqueue.c:2890 __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965 strp_done+0x53/0xd0 net/strparser/strparser.c:519 kcm_attach net/kcm/kcmsock.c:1429 [inline] kcm_attach_ioctl net/kcm/kcmsock.c:1490 [inline] kcm_ioctl+0x828/0xfb0 net/kcm/kcmsock.c:1701 sock_do_ioctl net/socket.c:974 [inline] sock_ioctl+0x2cc/0x4c0 net/socket.c:1071 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f3bb9d47279 RSP: 002b:00007f3bb86bc168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3bb9e59f80 RCX: 00007f3bb9d47279 RDX: 0000000020000280 RSI: 00000000000089e0 RDI: 0000000000000005 RBP: 00007f3bb9da1189 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe9406cbbf R14: 00007f3bb86bc300 R15: 0000000000022000 hfsplus: unable to load nls mapping "none" hfsplus: unable to parse mount options *** Guest State *** CR0: actual=0x0000000000000030, shadow=0x0000000060000010, gh_mask=fffffffffffffff7 CR4: actual=0x0000000000002050, shadow=0x0000000000000000, gh_mask=ffffffffffffe871 CR3 = 0x00000000fffbc000 RSP = 0x0000000000000f80 RIP = 0x0000000000000000 RFLAGS=0x00000002 DR7 = 0x0000000000000400 Sysenter RSP=0000000000000000 CS:RIP=0000:0000000000000000 CS: sel=0x0000, attr=0x0009b, limit=0x0000ffff, base=0x0000000000000000 DS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 SS: sel=0x0000, attr=0x00081, limit=0x0000ffff, base=0x0000000000000000 ES: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 FS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 GS: sel=0x0000, attr=0x00093, limit=0x0000ffff, base=0x0000000000000000 GDTR: limit=0x000007ff, base=0x0000000000001000 LDTR: sel=0x0008, attr=0x04082, limit=0x000007ff, base=0x0000000000001800 IDTR: limit=0x0000ffff, base=0x0000000000000000 TR: sel=0x0000, attr=0x0008b, limit=0x0000ffff, base=0x0000000000000000 EFER = 0x0000000000000000 PAT = 0x0007040600070406 DebugCtl = 0x0000000000000000 DebugExceptions = 0x0000000000000000 Interruptibility = 00000000 ActivityState = 00000000 *** Host State *** RIP = 0xffffffff8116119e RSP = 0xffff888057f579b8 CS=0010 SS=0018 DS=0000 ES=0000 FS=0000 GS=0000 TR=0040 FSBase=00007f3bb86bc700 GSBase=ffff8880ba500000 TRBase=fffffe000003e000 GDTBase=fffffe000003c000 IDTBase=fffffe0000000000 CR0=0000000080050033 CR3=00000000b3b50000 CR4=00000000003426e0 Sysenter RSP=fffffe000003e000 CS:RIP=0010:ffffffff87401690 EFER = 0x0000000000000d01 PAT = 0x0407050600070106 *** Control State *** PinBased=0000003f CPUBased=b699edfa SecondaryExec=000000ea EntryControls=0000d1ff ExitControls=002fefff ExceptionBitmap=00060042 PFECmask=00000000 PFECmatch=00000000 VMEntry: intr_info=00000000 errcode=00000000 ilen=00000000 VMExit: intr_info=00000000 errcode=00000000 ilen=00000000 reason=80000021 qualification=0000000000000000 IDTVectoring: info=00000000 errcode=00000000 TSC Offset = 0xffffffa4293679da EPT pointer = 0x000000009ad8801e Virtual processor ID = 0x0002 hfsplus: unable to find HFS+ superblock Zero length message leads to an empty skb