Extracting prog: 2m15.878983017s Minimizing prog: 10m44.599517074s Simplifying prog options: 15m11.46553036s Extracting C: 6m30.631832615s Simplifying C: 0s extracting reproducer from 34 programs testing a last program of every proc single: executing 9 programs separately with timeout 6m0s testing program (duration=6m0s, {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$PROG_LOAD_XDP-sendmmsg$inet6-socketpair$unix-bpf$MAP_CREATE-socket$inet6-bpf$MAP_UPDATE_ELEM_TAIL_CALL-bpf$MAP_DELETE_ELEM detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) sendmmsg$inet6(0xffffffffffffffff, &(0x7f0000001c80)=[{{0x0, 0x0, &(0x7f00000003c0)=[{&(0x7f0000000440)="14", 0x1}], 0x1}}], 0x1, 0x931766f6319eed40) socketpair$unix(0x1, 0x2, 0x0, &(0x7f0000000200)={0xffffffffffffffff, 0xffffffffffffffff}) r1 = bpf$MAP_CREATE(0x0, &(0x7f0000000140)=ANY=[@ANYBLOB="0f000000040000000400000015"], 0x50) socket$inet6(0xa, 0x6, 0xfffffffc) bpf$MAP_UPDATE_ELEM_TAIL_CALL(0x2, &(0x7f0000000740)={{r1, 0xffffffffffffffff}, &(0x7f00000006c0), &(0x7f0000000700)=r0}, 0x20) bpf$MAP_DELETE_ELEM(0x3, &(0x7f0000000580)={r2, &(0x7f0000000440)}, 0x20) program crashed: possible deadlock in lapbeth_device_event single: successfully extracted reproducer found reproducer with 7 syscalls minimizing guilty program testing program (duration=6m0s, {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$PROG_LOAD_XDP-sendmmsg$inet6-socketpair$unix-bpf$MAP_CREATE-socket$inet6-bpf$MAP_UPDATE_ELEM_TAIL_CALL detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) sendmmsg$inet6(0xffffffffffffffff, &(0x7f0000001c80)=[{{0x0, 0x0, &(0x7f00000003c0)=[{&(0x7f0000000440)="14", 0x1}], 0x1}}], 0x1, 0x931766f6319eed40) socketpair$unix(0x1, 0x2, 0x0, &(0x7f0000000200)={0xffffffffffffffff, 0xffffffffffffffff}) r1 = bpf$MAP_CREATE(0x0, &(0x7f0000000140)=ANY=[@ANYBLOB="0f000000040000000400000015"], 0x50) socket$inet6(0xa, 0x6, 0xfffffffc) bpf$MAP_UPDATE_ELEM_TAIL_CALL(0x2, &(0x7f0000000740)={{r1}, &(0x7f00000006c0), &(0x7f0000000700)=r0}, 0x20) program crashed: possible deadlock in lapbeth_device_event testing program (duration=6m0s, {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$PROG_LOAD_XDP-sendmmsg$inet6-socketpair$unix-bpf$MAP_CREATE-socket$inet6 detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) sendmmsg$inet6(0xffffffffffffffff, &(0x7f0000001c80)=[{{0x0, 0x0, &(0x7f00000003c0)=[{&(0x7f0000000440)="14", 0x1}], 0x1}}], 0x1, 0x931766f6319eed40) socketpair$unix(0x1, 0x2, 0x0, &(0x7f0000000200)) bpf$MAP_CREATE(0x0, &(0x7f0000000140)=ANY=[@ANYBLOB="0f000000040000000400000015"], 0x50) socket$inet6(0xa, 0x6, 0xfffffffc) program crashed: possible deadlock in lapbeth_device_event testing program (duration=6m0s, {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$PROG_LOAD_XDP-sendmmsg$inet6-socketpair$unix-bpf$MAP_CREATE detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) sendmmsg$inet6(0xffffffffffffffff, &(0x7f0000001c80)=[{{0x0, 0x0, &(0x7f00000003c0)=[{&(0x7f0000000440)="14", 0x1}], 0x1}}], 0x1, 0x931766f6319eed40) socketpair$unix(0x1, 0x2, 0x0, &(0x7f0000000200)) bpf$MAP_CREATE(0x0, &(0x7f0000000140)=ANY=[@ANYBLOB="0f000000040000000400000015"], 0x50) program crashed: possible deadlock in lapbeth_device_event testing program (duration=6m0s, {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$PROG_LOAD_XDP-sendmmsg$inet6-socketpair$unix detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) sendmmsg$inet6(0xffffffffffffffff, &(0x7f0000001c80)=[{{0x0, 0x0, &(0x7f00000003c0)=[{&(0x7f0000000440)="14", 0x1}], 0x1}}], 0x1, 0x931766f6319eed40) socketpair$unix(0x1, 0x2, 0x0, &(0x7f0000000200)) program crashed: possible deadlock in lapbeth_device_event testing program (duration=6m0s, {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$PROG_LOAD_XDP-sendmmsg$inet6 detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) sendmmsg$inet6(0xffffffffffffffff, &(0x7f0000001c80)=[{{0x0, 0x0, &(0x7f00000003c0)=[{&(0x7f0000000440)="14", 0x1}], 0x1}}], 0x1, 0x931766f6319eed40) program crashed: possible deadlock in lapbeth_device_event testing program (duration=6m0s, {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$PROG_LOAD_XDP detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, &(0x7f0000000540)={0x6, 0x15, &(0x7f0000000200)=@raw=[@func, @func, @func, @func={0x85, 0x0, 0x1, 0x0, 0x8}, @func, @snprintf, @func={0x85, 0x0, 0x1, 0x0, 0xfffffffffffffffe}, @cb_func={0x18, 0x5, 0x4, 0x0, 0xfffffffffffffffb}], &(0x7f0000000780)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, 0x25, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x90) program crashed: possible deadlock in lapbeth_device_event testing program (duration=6m0s, {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$PROG_LOAD_XDP detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, 0x0, 0x0) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=6m0s, {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$PROG_LOAD_XDP program crashed: no output from test machine a never seen crash title: no output from test machine, ignore simplifying guilty program options testing program (duration=6m0s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$PROG_LOAD_XDP detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, 0x0, 0x0) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=6m0s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): bpf$PROG_LOAD_XDP program crashed: no output from test machine a never seen crash title: no output from test machine, ignore testing program (duration=6m0s, {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$PROG_LOAD_XDP detailed listing: executing program 0: bpf$PROG_LOAD_XDP(0x5, 0x0, 0x0) program crashed: possible deadlock in lapbeth_device_event extracting C reproducer testing compiled C program (duration=6m0s, {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$PROG_LOAD_XDP program crashed: no output from test machine a never seen crash title: no output from test machine, ignore reproducing took 34m46.165598075s repro crashed as (corrupted=false): ============================================ WARNING: possible recursive locking detected 6.14.0-rc5-syzkaller-01152-g48c57a49c50a #0 Not tainted -------------------------------------------- dhcpcd/5501 is trying to acquire lock: ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2763 [inline] ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 but task is already holding lock: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] ffff88805f2ecd28 (&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/5501: #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: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] #1: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] #1: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 stack backtrace: CPU: 0 UID: 0 PID: 5501 Comm: dhcpcd Not tainted 6.14.0-rc5-syzkaller-01152-g48c57a49c50a #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: 0033:0x7f8413f36d49 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:00007ffdc354d6c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f8413e686c0 RCX: 00007f8413f36d49 RDX: 00007ffdc355d8b8 RSI: 0000000000008914 RDI: 0000000000000008 RBP: 00007ffdc356da78 R08: 00007ffdc355d878 R09: 00007ffdc355d828 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffdc355d8b8 R14: 0000000000000028 R15: 0000000000008914 final repro crashed as (corrupted=false): ============================================ WARNING: possible recursive locking detected 6.14.0-rc5-syzkaller-01152-g48c57a49c50a #0 Not tainted -------------------------------------------- dhcpcd/5501 is trying to acquire lock: ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2763 [inline] ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline] ffff88807ebb8d28 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460 but task is already holding lock: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] ffff88805f2ecd28 (&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/5501: #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: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2731 [inline] #1: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:40 [inline] #1: ffff88805f2ecd28 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67 stack backtrace: CPU: 0 UID: 0 PID: 5501 Comm: dhcpcd Not tainted 6.14.0-rc5-syzkaller-01152-g48c57a49c50a #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: 0033:0x7f8413f36d49 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:00007ffdc354d6c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f8413e686c0 RCX: 00007f8413f36d49 RDX: 00007ffdc355d8b8 RSI: 0000000000008914 RDI: 0000000000000008 RBP: 00007ffdc356da78 R08: 00007ffdc355d878 R09: 00007ffdc355d828 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffdc355d8b8 R14: 0000000000000028 R15: 0000000000008914