Extracting prog: 1m48.769612732s Minimizing prog: 15m56.023076091s Simplifying prog options: 14m9.831481197s Extracting C: 2m25.387677227s Simplifying C: 0s extracting reproducer from 30 programs first checking the prog from the crash report 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$BPF_PROG_RAW_TRACEPOINT_LOAD-bpf$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm-write$cgroup_subtree detailed listing: executing program 0: r0 = bpf$BPF_PROG_RAW_TRACEPOINT_LOAD(0x5, &(0x7f00000013c0)={0x11, 0x3, &(0x7f0000000880)=ANY=[], &(0x7f0000000300)='syzkaller\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x0, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00', r0}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) r1 = socket$kcm(0x10, 0x2, 0x0) write$cgroup_subtree(r1, &(0x7f0000000000)=ANY=[], 0xfe33) program crashed: possible deadlock in lapbeth_device_event single: successfully extracted reproducer found reproducer with 5 syscalls minimizing guilty program testing program (duration=49.992487782s, {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$BPF_PROG_RAW_TRACEPOINT_LOAD-bpf$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: r0 = bpf$BPF_PROG_RAW_TRACEPOINT_LOAD(0x5, &(0x7f00000013c0)={0x11, 0x3, &(0x7f0000000880)=ANY=[], &(0x7f0000000300)='syzkaller\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x0, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00', r0}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) socket$kcm(0x10, 0x2, 0x0) program crashed: possible deadlock in lapbeth_device_event testing program (duration=49.992487782s, {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$BPF_PROG_RAW_TRACEPOINT_LOAD-bpf$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm detailed listing: executing program 0: r0 = bpf$BPF_PROG_RAW_TRACEPOINT_LOAD(0x5, &(0x7f00000013c0)={0x11, 0x3, &(0x7f0000000880)=ANY=[], &(0x7f0000000300)='syzkaller\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x0, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00', r0}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) program did not crash testing program (duration=49.992487782s, {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$BPF_PROG_RAW_TRACEPOINT_LOAD-bpf$BPF_RAW_TRACEPOINT_OPEN-socket$kcm detailed listing: executing program 0: r0 = bpf$BPF_PROG_RAW_TRACEPOINT_LOAD(0x5, &(0x7f00000013c0)={0x11, 0x3, &(0x7f0000000880)=ANY=[], &(0x7f0000000300)='syzkaller\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x0, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00', r0}, 0x10) socket$kcm(0x10, 0x2, 0x0) program did not crash testing program (duration=49.992487782s, {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$BPF_PROG_RAW_TRACEPOINT_LOAD-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_PROG_RAW_TRACEPOINT_LOAD(0x5, &(0x7f00000013c0)={0x11, 0x3, &(0x7f0000000880)=ANY=[], &(0x7f0000000300)='syzkaller\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x0, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) socket$kcm(0x10, 0x2, 0x0) program did not crash testing program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00'}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) socket$kcm(0x10, 0x2, 0x0) program crashed: possible deadlock in lapbeth_device_event testing program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, 0x0, 0x0) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) socket$kcm(0x10, 0x2, 0x0) program did not crash testing program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={0x0}, 0x18) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, &(0x7f0000000180)=[{&(0x7f0000000000)="d8000000100081044e81f782db44b904021d080c48000000e8fe55a1180015000600142603600e120900210000000401a80016000a0001", 0x37}], 0x1}, 0x0) socket$kcm(0x10, 0x2, 0x0) program did not crash testing program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00'}, 0x10) sendmsg$kcm(0xffffffffffffffff, 0x0, 0x0) socket$kcm(0x10, 0x2, 0x0) program did not crash testing program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00'}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, 0x0}, 0x0) socket$kcm(0x10, 0x2, 0x0) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm program did not crash simplifying guilty program options testing program (duration=49.992487782s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00'}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, 0x0}, 0x0) socket$kcm(0x10, 0x2, 0x0) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=49.992487782s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm program did not crash testing program (duration=49.992487782s, {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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00'}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, 0x0}, 0x0) socket$kcm(0x10, 0x2, 0x0) program did not crash testing program (duration=49.992487782s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm detailed listing: executing program 0: bpf$BPF_RAW_TRACEPOINT_OPEN(0x11, &(0x7f00000000c0)={&(0x7f0000000040)='contention_end\x00'}, 0x10) sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000040)={0x0, 0x0, 0x0}, 0x0) socket$kcm(0x10, 0x2, 0x0) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=49.992487782s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 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$BPF_RAW_TRACEPOINT_OPEN-sendmsg$kcm-socket$kcm program did not crash reproducing took 33m27.601698502s repro crashed as (corrupted=false): ============================================ WARNING: possible recursive locking detected 6.14.0-rc5-syzkaller-01183-g40587f749df2 #0 Not tainted -------------------------------------------- dhcpcd/5503 is trying to acquire lock: ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2763 [inline] ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 but task is already holding lock: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] ffff888063954d28 (&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/5503: #0: ffffffff8fed6908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8fed6908 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x34c/0x1d80 net/ipv4/devinet.c:1121 #1: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] #1: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] #1: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 stack backtrace: CPU: 1 UID: 0 PID: 5503 Comm: dhcpcd Not tainted 6.14.0-rc5-syzkaller-01183-g40587f749df2 #0 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+0x483/0x620 kernel/locking/lockdep.c:3039 check_deadlock kernel/locking/lockdep.c:3091 [inline] validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730 netdev_lock include/linux/netdevice.h:2731 [inline] netif_napi_add_weight include/linux/netdevice.h:2763 [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+0x207/0x400 netif_change_flags+0xf0/0x1a0 net/core/dev.c:9443 dev_change_flags+0x146/0x270 net/core/dev_api.c:68 devinet_ioctl+0xea2/0x1d80 net/ipv4/devinet.c:1200 inet_ioctl+0x3d7/0x4f0 net/ipv4/af_inet.c:1001 sock_do_ioctl+0x158/0x460 net/socket.c:1190 sock_ioctl+0x626/0x8e0 net/socket.c:1309 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f014cab4d49 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:00007fff4e933378 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f014c9e66c0 RCX: 00007f014cab4d49 RDX: 00007fff4e943568 RSI: 0000000000008914 RDI: 0000000000000005 RBP: 00007fff4e953728 R08: 00007fff4e943528 R09: 00007fff4e9434d8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff4e943568 R14: 0000000000000028 R15: 0000000000008914 final repro crashed as (corrupted=false): ============================================ WARNING: possible recursive locking detected 6.14.0-rc5-syzkaller-01183-g40587f749df2 #0 Not tainted -------------------------------------------- dhcpcd/5503 is trying to acquire lock: ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2763 [inline] ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] ffff888028fb0d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 but task is already holding lock: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] ffff888063954d28 (&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/5503: #0: ffffffff8fed6908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #0: ffffffff8fed6908 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x34c/0x1d80 net/ipv4/devinet.c:1121 #1: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] #1: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] #1: ffff888063954d28 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 stack backtrace: CPU: 1 UID: 0 PID: 5503 Comm: dhcpcd Not tainted 6.14.0-rc5-syzkaller-01183-g40587f749df2 #0 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+0x483/0x620 kernel/locking/lockdep.c:3039 check_deadlock kernel/locking/lockdep.c:3091 [inline] validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730 netdev_lock include/linux/netdevice.h:2731 [inline] netif_napi_add_weight include/linux/netdevice.h:2763 [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+0x207/0x400 netif_change_flags+0xf0/0x1a0 net/core/dev.c:9443 dev_change_flags+0x146/0x270 net/core/dev_api.c:68 devinet_ioctl+0xea2/0x1d80 net/ipv4/devinet.c:1200 inet_ioctl+0x3d7/0x4f0 net/ipv4/af_inet.c:1001 sock_do_ioctl+0x158/0x460 net/socket.c:1190 sock_ioctl+0x626/0x8e0 net/socket.c:1309 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f014cab4d49 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:00007fff4e933378 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f014c9e66c0 RCX: 00007f014cab4d49 RDX: 00007fff4e943568 RSI: 0000000000008914 RDI: 0000000000000005 RBP: 00007fff4e953728 R08: 00007fff4e943528 R09: 00007fff4e9434d8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff4e943568 R14: 0000000000000028 R15: 0000000000008914