Extracting prog: 2m32.466759888s
Minimizing prog: 8m37.055051606s
Simplifying prog options: 0s
Extracting C: 29.388868647s
Simplifying C: 9m0.800593073s


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}}): socket$kcm-sendmsg$kcm
detailed listing:
executing program 0:
r0 = socket$kcm(0x10, 0x2, 0x0)
sendmsg$kcm(r0, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)=[{&(0x7f0000000180)="d8000000180081064e81f782db4cb904021d0800fd007c05e8fe55a10a000b000140020203600e41b0000900ac0006031100000016001500090002000000035c3b61c1d67f6f94007134cf6efb8000a007a290457f01a7cee4090000001fb791643a5ee4ce1b14d6d930dfe1d9d322fe7c9f8775730d16a4683f5ae24e25ccca9e00360db79826835d3a71d95667e006dcdf63951f215ce3bb9ad809d5e1cace81ed0bffece0b42a9ecbee5de6ccd40dd6e4edef3d93452a92954b43370e9703920723f9000000008af26c8b7b55f4d2a6823a45f28fcb1d", 0xd8}], 0x1}, 0x0)

program crashed: WARNING: bad unlock balance in __rtnl_unlock
single: successfully extracted reproducer
found reproducer with 2 syscalls
minimizing guilty program
testing program (duration=53.155295938s, {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}}): socket$kcm
detailed listing:
executing program 0:
socket$kcm(0x10, 0x2, 0x0)

program did not crash
testing program (duration=53.155295938s, {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}}): sendmsg$kcm
detailed listing:
executing program 0:
sendmsg$kcm(0xffffffffffffffff, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)=[{&(0x7f0000000180)="d8000000180081064e81f782db4cb904021d0800fd007c05e8fe55a10a000b000140020203600e41b0000900ac0006031100000016001500090002000000035c3b61c1d67f6f94007134cf6efb8000a007a290457f01a7cee4090000001fb791643a5ee4ce1b14d6d930dfe1d9d322fe7c9f8775730d16a4683f5ae24e25ccca9e00360db79826835d3a71d95667e006dcdf63951f215ce3bb9ad809d5e1cace81ed0bffece0b42a9ecbee5de6ccd40dd6e4edef3d93452a92954b43370e9703920723f9000000008af26c8b7b55f4d2a6823a45f28fcb1d", 0xd8}], 0x1}, 0x0)

program did not crash
testing program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
detailed listing:
executing program 0:
r0 = socket$kcm(0x10, 0x2, 0x0)
sendmsg$kcm(r0, 0x0, 0x0)

program did not crash
testing program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
detailed listing:
executing program 0:
r0 = socket$kcm(0x10, 0x2, 0x0)
sendmsg$kcm(r0, &(0x7f0000000000)={0x0, 0x0, 0x0}, 0x0)

program did not crash
testing program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
detailed listing:
executing program 0:
r0 = socket$kcm(0x10, 0x2, 0x0)
sendmsg$kcm(r0, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)=[{0x0}], 0x1}, 0x0)

program did not crash
testing program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
detailed listing:
executing program 0:
r0 = socket$kcm(0x10, 0x2, 0x0)
sendmsg$kcm(r0, &(0x7f0000000000)={0x0, 0x0, &(0x7f0000000140)=[{&(0x7f0000000180)}], 0x1}, 0x0)

program did not crash
extracting C reproducer
testing compiled C program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
simplifying C reproducer
testing compiled C program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
testing compiled C program (duration=53.155295938s, {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}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
testing compiled C program (duration=53.155295938s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:true Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
testing compiled C program (duration=53.155295938s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
testing compiled C program (duration=53.155295938s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:false HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
testing compiled C program (duration=53.155295938s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:false HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
testing compiled C program (duration=53.155295938s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$kcm-sendmsg$kcm
program crashed: WARNING: bad unlock balance in __rtnl_unlock
reproducing took 20m39.711295543s
repro crashed as (corrupted=false):
netlink: 'syz-executor243': attribute type 11 has an invalid length.
=====================================
WARNING: bad unlock balance detected!
6.14.0-rc4-syzkaller-00873-g3424291dd242 #0 Not tainted
-------------------------------------
syz-executor243/5826 is trying to release lock (rtnl_mutex) at:
[<ffffffff89d0e38c>] __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142
but there are no more locks to release!

other info that might help us debug this:
no locks held by syz-executor243/5826.

stack backtrace:
CPU: 1 UID: 0 PID: 5826 Comm: syz-executor243 Not tainted 6.14.0-rc4-syzkaller-00873-g3424291dd242 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0x25b/0x2d0 kernel/locking/lockdep.c:5289
 __lock_release kernel/locking/lockdep.c:5518 [inline]
 lock_release+0x47e/0xa30 kernel/locking/lockdep.c:5872
 __mutex_unlock_slowpath+0xec/0x800 kernel/locking/mutex.c:891
 __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142
 lwtunnel_valid_encap_type+0x38a/0x5f0 net/core/lwtunnel.c:169
 lwtunnel_valid_encap_type_attr+0x113/0x270 net/core/lwtunnel.c:209
 rtm_to_fib_config+0x949/0x14e0 net/ipv4/fib_frontend.c:808
 inet_rtm_newroute+0xf6/0x2a0 net/ipv4/fib_frontend.c:917
 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6919
 netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 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: 0033:0x7fd283ba13e9
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:00007ffeeb92d7c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffeeb92d998 RCX: 00007fd283ba13e9
RDX: 0000000000000000 RSI: 0000400000000000 RDI: 0000000000000003
RBP: 00007fd283c14610 R08: 0000000000000000 R09: 00007ffeeb92d998
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffeeb92d988 R14: 00000000000

final repro crashed as (corrupted=false):
netlink: 'syz-executor243': attribute type 11 has an invalid length.
=====================================
WARNING: bad unlock balance detected!
6.14.0-rc4-syzkaller-00873-g3424291dd242 #0 Not tainted
-------------------------------------
syz-executor243/5826 is trying to release lock (rtnl_mutex) at:
[<ffffffff89d0e38c>] __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142
but there are no more locks to release!

other info that might help us debug this:
no locks held by syz-executor243/5826.

stack backtrace:
CPU: 1 UID: 0 PID: 5826 Comm: syz-executor243 Not tainted 6.14.0-rc4-syzkaller-00873-g3424291dd242 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0x25b/0x2d0 kernel/locking/lockdep.c:5289
 __lock_release kernel/locking/lockdep.c:5518 [inline]
 lock_release+0x47e/0xa30 kernel/locking/lockdep.c:5872
 __mutex_unlock_slowpath+0xec/0x800 kernel/locking/mutex.c:891
 __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142
 lwtunnel_valid_encap_type+0x38a/0x5f0 net/core/lwtunnel.c:169
 lwtunnel_valid_encap_type_attr+0x113/0x270 net/core/lwtunnel.c:209
 rtm_to_fib_config+0x949/0x14e0 net/ipv4/fib_frontend.c:808
 inet_rtm_newroute+0xf6/0x2a0 net/ipv4/fib_frontend.c:917
 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6919
 netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 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: 0033:0x7fd283ba13e9
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:00007ffeeb92d7c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffeeb92d998 RCX: 00007fd283ba13e9
RDX: 0000000000000000 RSI: 0000400000000000 RDI: 0000000000000003
RBP: 00007fd283c14610 R08: 0000000000000000 R09: 00007ffeeb92d998
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffeeb92d988 R14: 00000000000