netlink: 4 bytes leftover after parsing attributes in process `syz-executor1'. ================================================================== BUG: KASAN: use-after-free in __list_add_valid+0x8f/0xac lib/list_debug.c:26 Read of size 8 at addr ffff8881b7ddcbb0 by task syz-fuzzer/5986 CPU: 0 PID: 5986 Comm: syz-fuzzer Not tainted 4.20.0-rc4+ #335 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: ip_tunnel: non-ECT from 0.0.0.0 with TOS=0x1 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x244/0x39d lib/dump_stack.c:113 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __list_add_valid+0x8f/0xac lib/list_debug.c:26 __list_add include/linux/list.h:60 [inline] list_add_tail include/linux/list.h:93 [inline] neigh_alloc net/core/neighbour.c:395 [inline] ___neigh_create+0x14b7/0x2600 net/core/neighbour.c:553 __neigh_create+0x30/0x40 net/core/neighbour.c:640 ip_finish_output2+0xb8b/0x1860 net/ipv4/ip_output.c:224 ip_finish_output+0x7fd/0xfa0 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_output+0x21d/0x8d0 net/ipv4/ip_output.c:405 dst_output include/net/dst.h:444 [inline] ip_local_out+0xc5/0x1b0 net/ipv4/ip_output.c:124 igmpv3_sendpack+0x1ad/0x2e0 net/ipv4/igmp.c:417 igmpv3_send_cr net/ipv4/igmp.c:705 [inline] igmp_ifc_timer_expire+0x7bb/0xbe0 net/ipv4/igmp.c:793 call_timer_fn+0x272/0x920 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x7e5/0xc70 kernel/time/timer.c:1682 run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1695 __do_softirq+0x308/0xb7e kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:804 RIP: 0010:check_memory_region+0x21/0x1b0 mm/kasan/kasan.c:266 Code: 2e 0f 1f 84 00 00 00 00 00 48 85 f6 0f 84 3c 01 00 00 48 b8 ff ff ff ff ff 7f ff ff 55 0f b6 d2 48 39 c7 48 89 e5 41 55 41 54 <53> 0f 86 11 01 00 00 4c 8d 5c 37 ff 48 89 fb 49 b9 00 00 00 00 00 RSP: 0018:ffff8881c2a36c60 EFLAGS: 00000216 ORIG_RAX: ffffffffffffff13 RAX: ffff7fffffffffff RBX: 0000000000000030 RCX: ffffffff8627ed17 RDX: 0000000000000000 RSI: 0000000000000030 RDI: ffff8881c6eff7a8 RBP: ffff8881c2a36c70 R08: ffffed1038ddff2b R09: ffffed1038ddff2a R10: ffffed1038ddff2a R11: ffff8881c6eff953 R12: ffff8881c6eff890 R13: ffff8881c6eff7a8 R14: ffff8881c6eff868 R15: ffff8881c2a36d68 memcpy+0x23/0x50 mm/kasan/kasan.c:302 memcpy include/linux/string.h:352 [inline] __copy_skb_header+0x127/0x6b0 net/core/skbuff.c:797 __skb_clone+0xe4/0xa00 net/core/skbuff.c:852 skb_clone+0x212/0x500 net/core/skbuff.c:1294 __tcp_transmit_skb+0x29c/0x3bb0 net/ipv4/tcp_output.c:1041 tcp_transmit_skb net/ipv4/tcp_output.c:1176 [inline] tcp_write_xmit+0x1085/0x5a40 net/ipv4/tcp_output.c:2388 __tcp_push_pending_frames+0xb2/0x340 net/ipv4/tcp_output.c:2561 tcp_push+0x66b/0x900 net/ipv4/tcp.c:735 tcp_sendmsg_locked+0x3267/0x3f80 net/ipv4/tcp.c:1406 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1443 inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:621 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:631 sock_write_iter+0x35e/0x5c0 net/socket.c:900 call_write_iter include/linux/fs.h:1857 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x6b8/0x9f0 fs/read_write.c:487 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x47fc44 Code: ff ff cc cc cc cc e8 9b 41 fb ff 48 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 45 31 d2 45 31 c0 45 31 c9 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 28 ff ff ff ff 48 c7 44 24 30 RSP: 002b:000000c4277b3328 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000047fc44 RDX: 00000000000000f0 RSI: 000000c4201203e0 RDI: 0000000000000003 RBP: 000000c4277b3378 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000c42000e210 R13: 000000000000007f R14: 0000000000b82980 R15: fffffffffffeffff Allocated by task 7827: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 __do_kmalloc mm/slab.c:3722 [inline] __kmalloc+0x15b/0x760 mm/slab.c:3731 kmalloc include/linux/slab.h:551 [inline] kzalloc include/linux/slab.h:741 [inline] neigh_alloc net/core/neighbour.c:375 [inline] ___neigh_create+0x13fc/0x2600 net/core/neighbour.c:553 __neigh_create+0x30/0x40 net/core/neighbour.c:640 neigh_create include/net/neighbour.h:319 [inline] __neigh_lookup_errno include/net/neighbour.h:511 [inline] arp_req_set+0x59d/0xaa0 net/ipv4/arp.c:1066 arp_ioctl+0x48b/0xae0 net/ipv4/arp.c:1230 inet_ioctl+0x237/0x360 net/ipv4/af_inet.c:932 sock_do_ioctl+0xeb/0x420 net/socket.c:950 sock_ioctl+0x313/0x690 net/socket.c:1074 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7832: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3817 __rcu_reclaim kernel/rcu/rcu.h:233 [inline] rcu_do_batch kernel/rcu/tree.c:2437 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline] rcu_process_callbacks+0x1140/0x1ac0 kernel/rcu/tree.c:2697 __do_softirq+0x308/0xb7e kernel/softirq.c:292 The buggy address belongs to the object at ffff8881b7ddc940 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 624 bytes inside of 1024-byte region [ffff8881b7ddc940, ffff8881b7ddcd40) The buggy address belongs to the page: page:ffffea0006df7700 count:1 mapcount:0 mapping:ffff8881da800ac0 index:0x0 compound_mapcount: 0 flags: 0x2fffc0000010200(slab|head) raw: 02fffc0000010200 ffffea0007656808 ffffea0007652888 ffff8881da800ac0 raw: 0000000000000000 ffff8881b7ddc040 0000000100000007 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881b7ddca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881b7ddcb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881b7ddcb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881b7ddcc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881b7ddcc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================