================================================================== BUG: KASAN: use-after-free in fib6_ifdown+0x1f8/0x220 net/ipv6/route.c:3473 Read of size 8 at addr ffff8801d47561c0 by task syz-executor7/30259 CPU: 1 PID: 30259 Comm: syz-executor7 Not tainted 4.15.0-rc7+ #259 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x25b/0x340 mm/kasan/report.c:409 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 fib6_ifdown+0x1f8/0x220 net/ipv6/route.c:3473 fib6_clean_node+0x333/0x4f0 net/ipv6/ip6_fib.c:1914 fib6_walk_continue+0x46c/0x8a0 net/ipv6/ip6_fib.c:1840 fib6_walk+0x91/0xf0 net/ipv6/ip6_fib.c:1888 fib6_clean_tree+0x1e6/0x340 net/ipv6/ip6_fib.c:1958 __fib6_clean_all+0x1f4/0x3a0 net/ipv6/ip6_fib.c:1974 fib6_clean_all+0x27/0x30 net/ipv6/ip6_fib.c:1985 rt6_ifdown+0xd1/0x6a0 net/ipv6/route.c:3490 addrconf_ifdown+0x134/0x14d0 net/ipv6/addrconf.c:3589 addrconf_notify+0x5eb/0x2270 net/ipv6/addrconf.c:3514 notifier_call_chain+0x136/0x2c0 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+0x32/0x60 net/core/dev.c:1691 call_netdevice_notifiers net/core/dev.c:1709 [inline] rollback_registered_many+0x8ad/0xdf0 net/core/dev.c:7255 rollback_registered+0x1be/0x3c0 net/core/dev.c:7297 unregister_netdevice_queue+0x2e3/0x5d0 net/core/dev.c:8285 unregister_netdevice include/linux/netdevice.h:2462 [inline] __tun_detach+0x1177/0x1550 drivers/net/tun.c:658 tun_detach drivers/net/tun.c:669 [inline] tun_chr_close+0x44/0x60 drivers/net/tun.c:2861 __fput+0x327/0x7e0 fs/file_table.c:210 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9bb/0x1ad0 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x73f/0x16c0 kernel/signal.c:2335 do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:264 [inline] do_syscall_64+0x6dc/0x920 arch/x86/entry/common.c:290 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x452ac9 RSP: 002b:00007fa305bdfce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000000 RBX: 000000000071bec8 RCX: 0000000000452ac9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000071bec8 RBP: 000000000071bec8 R08: 00000000000002fa R09: 000000000071bea0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000a2f7ef R14: 00007fa305be09c0 R15: 0000000000000000 Allocated by task 27621: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544 dst_alloc+0x11f/0x1a0 net/core/dst.c:107 __ip6_dst_alloc+0x35/0x90 net/ipv6/route.c:361 ip6_dst_alloc+0x29/0xb0 net/ipv6/route.c:376 ip6_route_info_create+0x4ff/0x2d40 net/ipv6/route.c:2537 ip6_route_add+0xa2/0x190 net/ipv6/route.c:2774 ipv6_route_ioctl+0x4db/0x6b0 net/ipv6/route.c:3294 inet6_ioctl+0xef/0x1e0 net/ipv6/af_inet6.c:520 sock_do_ioctl+0x65/0xb0 net/socket.c:966 sock_ioctl+0x2c2/0x440 net/socket.c:1063 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x23/0x9a Freed by task 16: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3488 [inline] kmem_cache_free+0x83/0x2a0 mm/slab.c:3746 dst_destroy+0x216/0x330 net/core/dst.c:138 dst_destroy_rcu+0x16/0x20 net/core/dst.c:151 __rcu_reclaim kernel/rcu/rcu.h:195 [inline] rcu_do_batch kernel/rcu/tree.c:2758 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:3012 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2979 [inline] rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2996 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 The buggy address belongs to the object at ffff8801d47561c0 which belongs to the cache ip6_dst_cache of size 384 The buggy address is located 0 bytes inside of 384-byte region [ffff8801d47561c0, ffff8801d4756340) The buggy address belongs to the page: page:ffffea000751d580 count:1 mapcount:0 mapping:ffff8801d4756000 index:0xffff8801d4756a80 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801d4756000 ffff8801d4756a80 0000000100000008 raw: ffff8801d3032638 ffff8801d3032638 ffff8801d303bd80 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d4756080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d4756100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801d4756180: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8801d4756200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d4756280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================