Extracting prog: 8m6.774477831s Minimizing prog: 6m54.653485497s Simplifying prog options: 6m2.440275256s Extracting C: 2m7.96751674s Simplifying C: 0s extracting reproducer from 1 programs testing a last program of every proc single: executing 1 programs separately with timeout 30s testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY-openat$cgroup_root-bpf$PROG_LOAD-bpf$BPF_PROG_DETACH detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x7, &(0x7f0000000000)='cgroup\x00'}, 0x30) r0 = openat$cgroup_root(0xffffffffffffff9c, &(0x7f0000000000), 0x200002, 0x0) r1 = bpf$PROG_LOAD(0x5, &(0x7f0000000080)={0x9, 0x4, &(0x7f00000008c0)=ANY=[@ANYBLOB="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"], &(0x7f0000000100)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, @cgroup_sock, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x70) bpf$BPF_PROG_DETACH(0x8, &(0x7f0000000040)={@cgroup=r0, r1, 0x2, 0x2, 0x0, @void, @value}, 0x10) program crashed: possible deadlock in lapbeth_device_event single: successfully extracted reproducer found reproducer with 4 syscalls minimizing guilty program testing program (duration=54.039701013s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY-openat$cgroup_root-bpf$PROG_LOAD detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x7, &(0x7f0000000000)='cgroup\x00'}, 0x30) openat$cgroup_root(0xffffffffffffff9c, &(0x7f0000000000), 0x200002, 0x0) bpf$PROG_LOAD(0x5, &(0x7f0000000080)={0x9, 0x4, &(0x7f00000008c0)=ANY=[@ANYBLOB="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"], &(0x7f0000000100)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, @cgroup_sock, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x70) program crashed: possible deadlock in lapbeth_device_event testing program (duration=54.039701013s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY-openat$cgroup_root detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x7, &(0x7f0000000000)='cgroup\x00'}, 0x30) openat$cgroup_root(0xffffffffffffff9c, &(0x7f0000000000), 0x200002, 0x0) program crashed: possible deadlock in lapbeth_device_event testing program (duration=54.039701013s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x7, &(0x7f0000000000)='cgroup\x00'}, 0x30) program crashed: possible deadlock in lapbeth_device_event testing program (duration=54.039701013s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, 0x0, 0x0) program did not crash testing program (duration=54.039701013s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x0, 0x0}, 0x30) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=54.039701013s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY program did not crash simplifying guilty program options testing program (duration=54.039701013s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x0, 0x0}, 0x30) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=54.039701013s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY program did not crash testing program (duration=54.039701013s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY detailed listing: executing program 0: bpf$BPF_TASK_FD_QUERY(0x14, &(0x7f0000000180)={0x0, 0xffffffffffffffff, 0x0, 0x0, 0x0}, 0x30) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=54.039701013s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_TASK_FD_QUERY program did not crash reproducing took 23m33.126984274s repro crashed as (corrupted=false): ============================================ WARNING: possible recursive locking detected 6.14.0-syzkaller-g25601e85441d #0 Not tainted -------------------------------------------- dhcpcd/5504 is trying to acquire lock: ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline] ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2783 [inline] ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 but task is already holding lock: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline] ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&dev->lock); lock(&dev->lock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by dhcpcd/5504: #0: ffffffff900fb888 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff900fb888 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x34e/0x1d80 net/ipv4/devinet.c:1121 #1: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline] #1: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] #1: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 stack backtrace: CPU: 0 UID: 0 PID: 5504 Comm: dhcpcd Not tainted 6.14.0-syzkaller-g25601e85441d #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_deadlock_bug+0x2be/0x2d0 kernel/locking/lockdep.c:3042 check_deadlock kernel/locking/lockdep.c:3094 [inline] validate_chain+0x928/0x24e0 kernel/locking/lockdep.c:3896 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746 netdev_lock include/linux/netdevice.h:2751 [inline] netif_napi_add_weight include/linux/netdevice.h:2783 [inline] lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85 __dev_notify_flags+0x209/0x410 net/core/dev.c:-1 netif_change_flags+0xf0/0x1a0 net/core/dev.c:9438 dev_change_flags+0x146/0x270 net/core/dev_api.c:68 devinet_ioctl+0xea4/0x1d80 net/ipv4/devinet.c:1200 inet_ioctl+0x3d9/0x4f0 net/ipv4/af_inet.c:1001 sock_do_ioctl+0x15a/0x490 net/socket.c:1190 sock_ioctl+0x644/0x900 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f266b48dd49 Code: 5c c3 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 76 10 48 8b 15 ae 60 0d 00 f7 d8 41 83 c8 RSP: 002b:00007fffb7e6f418 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f266b3bf6c0 RCX: 00007f266b48dd49 RDX: 00007fffb7e7f608 RSI: 0000000000008914 RDI: 0000000000000018 RBP: 00007fffb7e8f7c8 R08: 00007fffb7e7f5c8 R09: 00007fffb7e7f578 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffb7e7f608 R14: 0000000000000028 R15: 0000000000008914 final repro crashed as (corrupted=false): ============================================ WARNING: possible recursive locking detected 6.14.0-syzkaller-g25601e85441d #0 Not tainted -------------------------------------------- dhcpcd/5504 is trying to acquire lock: ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline] ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2783 [inline] ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] ffff888028594d30 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 but task is already holding lock: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline] ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&dev->lock); lock(&dev->lock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by dhcpcd/5504: #0: ffffffff900fb888 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff900fb888 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x34e/0x1d80 net/ipv4/devinet.c:1121 #1: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline] #1: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline] #1: ffff88806d8d0d30 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 stack backtrace: CPU: 0 UID: 0 PID: 5504 Comm: dhcpcd Not tainted 6.14.0-syzkaller-g25601e85441d #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_deadlock_bug+0x2be/0x2d0 kernel/locking/lockdep.c:3042 check_deadlock kernel/locking/lockdep.c:3094 [inline] validate_chain+0x928/0x24e0 kernel/locking/lockdep.c:3896 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746 netdev_lock include/linux/netdevice.h:2751 [inline] netif_napi_add_weight include/linux/netdevice.h:2783 [inline] lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85 __dev_notify_flags+0x209/0x410 net/core/dev.c:-1 netif_change_flags+0xf0/0x1a0 net/core/dev.c:9438 dev_change_flags+0x146/0x270 net/core/dev_api.c:68 devinet_ioctl+0xea4/0x1d80 net/ipv4/devinet.c:1200 inet_ioctl+0x3d9/0x4f0 net/ipv4/af_inet.c:1001 sock_do_ioctl+0x15a/0x490 net/socket.c:1190 sock_ioctl+0x644/0x900 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f266b48dd49 Code: 5c c3 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 76 10 48 8b 15 ae 60 0d 00 f7 d8 41 83 c8 RSP: 002b:00007fffb7e6f418 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f266b3bf6c0 RCX: 00007f266b48dd49 RDX: 00007fffb7e7f608 RSI: 0000000000008914 RDI: 0000000000000018 RBP: 00007fffb7e8f7c8 R08: 00007fffb7e7f5c8 R09: 00007fffb7e7f578 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffb7e7f608 R14: 0000000000000028 R15: 0000000000008914