================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: use-after-free in refcount_sub_and_test_checked+0x9a/0x350 lib/refcount.c:179 Read of size 4 at addr ffff880193cab444 by task syz-executor1/4368 CPU: 1 PID: 4368 Comm: syz-executor1 Not tainted 4.18.0-rc7-next-20180802+ #30 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] refcount_sub_and_test_checked+0x9a/0x350 lib/refcount.c:179 refcount_dec_and_test_checked+0x1a/0x20 lib/refcount.c:212 fib6_metrics_release+0x4f/0x90 net/ipv6/ip6_fib.c:178 fib6_drop_pcpu_from net/ipv6/ip6_fib.c:899 [inline] fib6_purge_rt+0x5ec/0x7f0 net/ipv6/ip6_fib.c:934 fib6_del_route net/ipv6/ip6_fib.c:1784 [inline] fib6_del+0xc11/0x1310 net/ipv6/ip6_fib.c:1815 fib6_clean_node+0x3ee/0x5e0 net/ipv6/ip6_fib.c:1976 fib6_walk_continue+0x4b1/0x8e0 net/ipv6/ip6_fib.c:1899 fib6_walk+0x95/0xf0 net/ipv6/ip6_fib.c:1947 fib6_clean_tree+0x1ea/0x360 net/ipv6/ip6_fib.c:2024 __fib6_clean_all+0x21c/0x420 net/ipv6/ip6_fib.c:2040 fib6_clean_all+0x27/0x30 net/ipv6/ip6_fib.c:2051 rt6_sync_down_dev net/ipv6/route.c:4083 [inline] rt6_disable_ip+0x111/0x7e0 net/ipv6/route.c:4088 addrconf_ifdown+0x16f/0x1670 net/ipv6/addrconf.c:3648 addrconf_notify+0x6e9/0x27f0 net/ipv6/addrconf.c:3573 notifier_call_chain+0x180/0x390 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1734 call_netdevice_notifiers net/core/dev.c:1752 [inline] dev_close_many+0x447/0x8d0 net/core/dev.c:1504 rollback_registered_many+0x539/0x1250 net/core/dev.c:7919 rollback_registered+0x1e9/0x420 net/core/dev.c:7984 unregister_netdevice_queue+0x32f/0x660 net/core/dev.c:9028 unregister_netdevice include/linux/netdevice.h:2589 [inline] __tun_detach+0x11d1/0x15e0 drivers/net/tun.c:728 tun_detach drivers/net/tun.c:745 [inline] tun_chr_close+0xe3/0x180 drivers/net/tun.c:3271 __fput+0x376/0x8a0 fs/file_table.c:279 ____fput+0x15/0x20 fs/file_table.c:312 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1b25/0x2760 kernel/exit.c:869 do_group_exit+0x177/0x440 kernel/exit.c:972 __do_sys_exit_group kernel/exit.c:983 [inline] __se_sys_exit_group kernel/exit.c:981 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:981 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456a09 Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc76fa5b88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000456a09 RDX: 00000000004104e0 RSI: 0000000000a44bd0 RDI: 0000000000000045 RBP: 00000000004c1904 R08: 000000000000000b R09: 0000000000000000 R10: 0000000000c94940 R11: 0000000000000246 R12: 0000000000c95940 R13: 0000000000000000 R14: 00000000000000a8 R15: badc0ffeebadface Allocated by task 8880: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:707 [inline] fib6_metric_set+0x163/0x2c0 net/ipv6/ip6_fib.c:645 fib6_add_rt2node+0xe36/0x27f0 net/ipv6/ip6_fib.c:1000 fib6_add+0xaae/0x14d0 net/ipv6/ip6_fib.c:1308 __ip6_ins_rt+0x54/0x80 net/ipv6/route.c:1163 ip6_route_add+0x6d/0xc0 net/ipv6/route.c:3171 addrconf_prefix_route.isra.48+0x51d/0x720 net/ipv6/addrconf.c:2345 inet6_addr_modify net/ipv6/addrconf.c:4625 [inline] inet6_rtm_newaddr+0x112e/0x1b50 net/ipv6/addrconf.c:4741 rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4711 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4729 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343 netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:632 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2115 __sys_sendmsg+0x11d/0x290 net/socket.c:2153 __do_sys_sendmsg net/socket.c:2162 [inline] __se_sys_sendmsg net/socket.c:2160 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2160 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 4368: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xd9/0x260 mm/slab.c:3813 fib6_metrics_release+0x77/0x90 net/ipv6/ip6_fib.c:179 fib6_drop_pcpu_from net/ipv6/ip6_fib.c:899 [inline] fib6_purge_rt+0x5ec/0x7f0 net/ipv6/ip6_fib.c:934 fib6_del_route net/ipv6/ip6_fib.c:1784 [inline] fib6_del+0xc11/0x1310 net/ipv6/ip6_fib.c:1815 fib6_clean_node+0x3ee/0x5e0 net/ipv6/ip6_fib.c:1976 fib6_walk_continue+0x4b1/0x8e0 net/ipv6/ip6_fib.c:1899 fib6_walk+0x95/0xf0 net/ipv6/ip6_fib.c:1947 fib6_clean_tree+0x1ea/0x360 net/ipv6/ip6_fib.c:2024 __fib6_clean_all+0x21c/0x420 net/ipv6/ip6_fib.c:2040 fib6_clean_all+0x27/0x30 net/ipv6/ip6_fib.c:2051 rt6_sync_down_dev net/ipv6/route.c:4083 [inline] rt6_disable_ip+0x111/0x7e0 net/ipv6/route.c:4088 addrconf_ifdown+0x16f/0x1670 net/ipv6/addrconf.c:3648 addrconf_notify+0x6e9/0x27f0 net/ipv6/addrconf.c:3573 notifier_call_chain+0x180/0x390 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1734 call_netdevice_notifiers net/core/dev.c:1752 [inline] dev_close_many+0x447/0x8d0 net/core/dev.c:1504 rollback_registered_many+0x539/0x1250 net/core/dev.c:7919 rollback_registered+0x1e9/0x420 net/core/dev.c:7984 unregister_netdevice_queue+0x32f/0x660 net/core/dev.c:9028 unregister_netdevice include/linux/netdevice.h:2589 [inline] __tun_detach+0x11d1/0x15e0 drivers/net/tun.c:728 tun_detach drivers/net/tun.c:745 [inline] tun_chr_close+0xe3/0x180 drivers/net/tun.c:3271 __fput+0x376/0x8a0 fs/file_table.c:279 ____fput+0x15/0x20 fs/file_table.c:312 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1b25/0x2760 kernel/exit.c:869 do_group_exit+0x177/0x440 kernel/exit.c:972 __do_sys_exit_group kernel/exit.c:983 [inline] __se_sys_exit_group kernel/exit.c:981 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:981 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff880193cab400 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 68 bytes inside of 96-byte region [ffff880193cab400, ffff880193cab460) The buggy address belongs to the page: page:ffffea00064f2ac0 count:1 mapcount:0 mapping:ffff8801dac004c0 index:0xffff880193cab500 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea000766d048 ffffea0007626088 ffff8801dac004c0 raw: ffff880193cab500 ffff880193cab000 000000010000000a 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff880193cab300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff880193cab380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff880193cab400: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff880193cab480: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff880193cab500: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ==================================================================