Extracting prog: 1m7.061611682s
Minimizing prog: 7m42.804287425s
Simplifying prog options: 0s
Extracting C: 34.041743887s
Simplifying C: 4m15.257129878s


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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
close(0x3)
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program crashed: KASAN: use-after-free Write in pppol2tp_release
single: successfully extracted reproducer
found reproducer with 7 syscalls
minimizing guilty program
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3
detailed listing:
executing program 0:
close(0x3)
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040), 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
close(0x3)
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
ioctl$EXT4_IOC_GETFSUUID(0xffffffffffffffff, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
close(0x3)
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$pppl2tp-socket$inet6_udp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
close(0x3)
socket$pppl2tp(0x18, 0x1, 0x1)
socket$inet6_udp(0xa, 0x2, 0x0)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r0=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r0, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$pppl2tp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
close(0x3)
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, 0xffffffffffffffff, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r1=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r1, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): close-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
close(0x3)
r0 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(0xffffffffffffffff, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r0, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r1=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r1, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, 0x0, 0x0)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r1=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r1, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, 0x0, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(0x0, 0x0)
ioctl$EXT4_IOC_GETFSUUID(0xffffffffffffffff, 0x40047452, 0x0)

program did not crash
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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, 0x0, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(0xffffffffffffffff, 0x40047452, 0x0)

program did not crash
extracting C reproducer
testing compiled C 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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Write in pppol2tp_release
simplifying C reproducer
testing compiled C program (duration=30s, {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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
testing compiled C program (duration=30s, {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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Write in rcu_segcblist_enqueue
a never seen crash title: KASAN: use-after-free Write in rcu_segcblist_enqueue, ignore
testing compiled C program (duration=30s, {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:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
testing compiled C program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
testing compiled C program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
testing program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
validation run: crashed=true
testing program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
validation run: crashed=true
testing program (duration=30s, {Threaded:false Repeat:true 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 CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-sendfile-syz_clone3-ioctl$EXT4_IOC_GETFSUUID
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x8, 0x0, 0x0, 0x0, {0xa, 0x0, 0x0, @rand_addr=' \x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'}}}, 0x32)
sendfile(0xffffffffffffffff, 0xffffffffffffffff, &(0x7f0000000040)=0x3, 0xac5)
syz_clone3(&(0x7f0000000900)={0x23800000, &(0x7f0000000040)=<r2=>0xffffffffffffffff, 0x0, 0x0, {0x27}, 0x0, 0x0, 0x0, 0x0}, 0x58)
ioctl$EXT4_IOC_GETFSUUID(r2, 0x40047452, 0x0)

program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
validation run: crashed=true
reproducing took 15m27.599487799s
repro crashed as (corrupted=false):
==================================================================
BUG: KASAN: use-after-free in pppol2tp_sock_to_session+0x1a0/0x1b0 net/l2tp/l2tp_ppp.c:156
Read of size 4 at addr ffff8881136b9800 by task syz.2.17/376

CPU: 0 PID: 376 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350
 pppol2tp_sock_to_session+0x1a0/0x1b0 net/l2tp/l2tp_ppp.c:156
 pppol2tp_release+0x150/0x2b0 net/l2tp/l2tp_ppp.c:434
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1390
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xb0d/0x29f0 kernel/exit.c:896
 __do_sys_exit kernel/exit.c:1006 [inline]
 __se_sys_exit kernel/exit.c:1004 [inline]
 __x64_sys_exit+0x40/0x40 kernel/exit.c:1004
 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8d1ed9fb19
Code: Unable to access opcode bytes at 0x7f8d1ed9faef.
RSP: 002b:00007ffd99afb7b8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f8d1ed9fb19
RDX: 00007f8d1ed5ac97 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8d1ee37b70 R08: 0000000000000000 R09: 0000000000000058
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d1f025fac R14: 00007f8d1f025fa0 R15: 00007f8d1f025fa0
 </TASK>

Allocated by task 375:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 __do_kmalloc_node mm/slab_common.c:938 [inline]
 __kmalloc+0xb4/0x1e0 mm/slab_common.c:951
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1614
 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
 __sys_connect_file net/socket.c:2001 [inline]
 __sys_connect+0x3da/0x460 net/socket.c:2018
 __do_sys_connect net/socket.c:2028 [inline]
 __se_sys_connect net/socket.c:2025 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2025
 x64_sys_call+0x88d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 43:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
 kfree+0x6f/0xf0 mm/slab_common.c:990
 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
 l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193
 l2tp_session_delete+0x3df/0x4d0 net/l2tp/l2tp_core.c:1587
 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1233 [inline]
 l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1271
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff8881136b9800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8881136b9800, ffff8881136b9a00)

The buggy address belongs to the physical page:
page:ffffea00044dae00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1136b8
head:ffffea00044dae00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea0004490700 dead000000000003 ffff888100042f00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 108, tgid 108 (udevd), ts 5475812989, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2673
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2680
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4587
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5931
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
 __do_kmalloc_node mm/slab_common.c:937 [inline]
 __kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
 kmalloc_reserve net/core/skbuff.c:449 [inline]
 __alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
 alloc_skb include/linux/skbuff.h:1322 [inline]
 alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6189
 sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2770
 unix_dgram_sendmsg+0x5c1/0x1710 net/unix/af_unix.c:1959
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 sock_write_iter+0x2ea/0x3f0 net/socket.c:1134
 call_write_iter include/linux/fs.h:2282 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x5ef/0xd00 fs/read_write.c:584
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881136b9700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881136b9780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881136b9800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8881136b9880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881136b9900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
------------[ cut here ]------------
WARNING: CPU: 0 PID: 376 at net/l2tp/l2tp_ppp.c:156 pppol2tp_sock_to_session+0x167/0x1b0 net/l2tp/l2tp_ppp.c:156
Modules linked in:
CPU: 0 PID: 376 Comm: syz.2.17 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:pppol2tp_sock_to_session+0x167/0x1b0 net/l2tp/l2tp_ppp.c:156
Code: 5d c3 e8 fc b9 d4 fc be 02 00 00 00 eb 0a e8 f0 b9 d4 fc be 01 00 00 00 4c 89 f7 e8 83 bd cc fd e9 0f ff ff ff e8 d9 b9 d4 fc <0f> 0b 48 89 df e8 ff 00 00 00 eb bd e8 c8 b9 d4 fc 4c 89 f7 be 03
RSP: 0018:ffffc900009b7b90 EFLAGS: 00010293
RAX: ffffffff849cb847 RBX: ffff888113ec2000 RCX: ffff888112a03cc0
RDX: 0000000000000000 RSI: 00000000117c6ec0 RDI: 000000000c04eb7d
RBP: ffffc900009b7bb0 R08: ffffffff87b777e7 R09: 1ffffffff0f6eefc
R10: dffffc0000000000 R11: fffffbfff0f6eefd R12: dffffc0000000000
R13: dffffc0000000000 R14: 00000000117c6ec0 R15: ffff8881136b9800
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8d1fb58060 CR3: 000000000700f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pppol2tp_release+0x150/0x2b0 net/l2tp/l2tp_ppp.c:434
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1390
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xb0d/0x29f0 kernel/exit.c:896
 __do_sys_exit kernel/exit.c:1006 [inline]
 __se_sys_exit kernel/exit.c:1004 [inline]
 __x64_sys_exit+0x40/0x40 kernel/exit.c:1004
 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8d1ed9fb19
Code: Unable to access opcode bytes at 0x7f8d1ed9faef.
RSP: 002b:00007ffd99afb7b8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f8d1ed9fb19
RDX: 00007f8d1ed5ac97 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8d1ee37b70 R08: 0000000000000000 R09: 0000000000000058
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d1f025fac R14: 00007f8d1f025fa0 R15: 00007f8d1f025fa0
 </TASK>
---[ end trace 0000000000000000 ]---

final repro crashed as (corrupted=false):
==================================================================
BUG: KASAN: use-after-free in pppol2tp_sock_to_session+0x1a0/0x1b0 net/l2tp/l2tp_ppp.c:156
Read of size 4 at addr ffff8881136b9800 by task syz.2.17/376

CPU: 0 PID: 376 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350
 pppol2tp_sock_to_session+0x1a0/0x1b0 net/l2tp/l2tp_ppp.c:156
 pppol2tp_release+0x150/0x2b0 net/l2tp/l2tp_ppp.c:434
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1390
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xb0d/0x29f0 kernel/exit.c:896
 __do_sys_exit kernel/exit.c:1006 [inline]
 __se_sys_exit kernel/exit.c:1004 [inline]
 __x64_sys_exit+0x40/0x40 kernel/exit.c:1004
 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8d1ed9fb19
Code: Unable to access opcode bytes at 0x7f8d1ed9faef.
RSP: 002b:00007ffd99afb7b8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f8d1ed9fb19
RDX: 00007f8d1ed5ac97 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8d1ee37b70 R08: 0000000000000000 R09: 0000000000000058
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d1f025fac R14: 00007f8d1f025fa0 R15: 00007f8d1f025fa0
 </TASK>

Allocated by task 375:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 __do_kmalloc_node mm/slab_common.c:938 [inline]
 __kmalloc+0xb4/0x1e0 mm/slab_common.c:951
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1614
 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
 __sys_connect_file net/socket.c:2001 [inline]
 __sys_connect+0x3da/0x460 net/socket.c:2018
 __do_sys_connect net/socket.c:2028 [inline]
 __se_sys_connect net/socket.c:2025 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2025
 x64_sys_call+0x88d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 43:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
 kfree+0x6f/0xf0 mm/slab_common.c:990
 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
 l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193
 l2tp_session_delete+0x3df/0x4d0 net/l2tp/l2tp_core.c:1587
 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1233 [inline]
 l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1271
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff8881136b9800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8881136b9800, ffff8881136b9a00)

The buggy address belongs to the physical page:
page:ffffea00044dae00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1136b8
head:ffffea00044dae00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 ffffea0004490700 dead000000000003 ffff888100042f00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 108, tgid 108 (udevd), ts 5475812989, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2673
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2680
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4587
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5931
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
 __do_kmalloc_node mm/slab_common.c:937 [inline]
 __kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
 kmalloc_reserve net/core/skbuff.c:449 [inline]
 __alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
 alloc_skb include/linux/skbuff.h:1322 [inline]
 alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6189
 sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2770
 unix_dgram_sendmsg+0x5c1/0x1710 net/unix/af_unix.c:1959
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 sock_write_iter+0x2ea/0x3f0 net/socket.c:1134
 call_write_iter include/linux/fs.h:2282 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x5ef/0xd00 fs/read_write.c:584
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881136b9700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881136b9780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881136b9800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8881136b9880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881136b9900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
------------[ cut here ]------------
WARNING: CPU: 0 PID: 376 at net/l2tp/l2tp_ppp.c:156 pppol2tp_sock_to_session+0x167/0x1b0 net/l2tp/l2tp_ppp.c:156
Modules linked in:
CPU: 0 PID: 376 Comm: syz.2.17 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:pppol2tp_sock_to_session+0x167/0x1b0 net/l2tp/l2tp_ppp.c:156
Code: 5d c3 e8 fc b9 d4 fc be 02 00 00 00 eb 0a e8 f0 b9 d4 fc be 01 00 00 00 4c 89 f7 e8 83 bd cc fd e9 0f ff ff ff e8 d9 b9 d4 fc <0f> 0b 48 89 df e8 ff 00 00 00 eb bd e8 c8 b9 d4 fc 4c 89 f7 be 03
RSP: 0018:ffffc900009b7b90 EFLAGS: 00010293
RAX: ffffffff849cb847 RBX: ffff888113ec2000 RCX: ffff888112a03cc0
RDX: 0000000000000000 RSI: 00000000117c6ec0 RDI: 000000000c04eb7d
RBP: ffffc900009b7bb0 R08: ffffffff87b777e7 R09: 1ffffffff0f6eefc
R10: dffffc0000000000 R11: fffffbfff0f6eefd R12: dffffc0000000000
R13: dffffc0000000000 R14: 00000000117c6ec0 R15: ffff8881136b9800
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8d1fb58060 CR3: 000000000700f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pppol2tp_release+0x150/0x2b0 net/l2tp/l2tp_ppp.c:434
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1390
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xb0d/0x29f0 kernel/exit.c:896
 __do_sys_exit kernel/exit.c:1006 [inline]
 __se_sys_exit kernel/exit.c:1004 [inline]
 __x64_sys_exit+0x40/0x40 kernel/exit.c:1004
 x64_sys_call+0x67/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:61
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8d1ed9fb19
Code: Unable to access opcode bytes at 0x7f8d1ed9faef.
RSP: 002b:00007ffd99afb7b8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f8d1ed9fb19
RDX: 00007f8d1ed5ac97 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8d1ee37b70 R08: 0000000000000000 R09: 0000000000000058
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d1f025fac R14: 00007f8d1f025fa0 R15: 00007f8d1f025fa0
 </TASK>
---[ end trace 0000000000000000 ]---