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BUG: KASAN: use-after-free in rtnetlink_put_metrics+0x621/0x690 net/core/rtnetlink.c:754
Read of size 4 at addr ffff8801c7aec580 by task syz-executor5/4433

CPU: 0 PID: 4433 Comm: syz-executor5 Not tainted 4.18.0-rc7+ #36
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __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+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 rtnetlink_put_metrics+0x621/0x690 net/core/rtnetlink.c:754
 rt6_fill_node+0x7d9/0x1540 net/ipv6/route.c:4753
ip6_tunnel: non-ECT from fe80:0000:0000:0000:0000:0000:0000:00bb with DS=0x5
 inet6_rt_notify+0x161/0x2c0 net/ipv6/route.c:4985
ip6_tunnel: non-ECT from fe80:0000:0000:0000:0000:0000:0000:00bb with DS=0x5
 fib6_del_route net/ipv6/ip6_fib.c:1788 [inline]
 fib6_del+0xf4d/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 net/ipv6/ip6_fib.c:2051 [inline]
 fib6_run_gc+0x182/0x3d0 net/ipv6/ip6_fib.c:2107
 fib6_gc_timer_cb+0x20/0x30 net/ipv6/ip6_fib.c:2124
 call_timer_fn+0x242/0x970 kernel/time/timer.c:1326
 expire_timers kernel/time/timer.c:1363 [inline]
 __run_timers+0x7a6/0xc70 kernel/time/timer.c:1666
 run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
 __do_softirq+0x2e8/0xb17 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:372 [inline]
 irq_exit+0x1d4/0x210 kernel/softirq.c:412
 exiting_irq arch/x86/include/asm/apic.h:527 [inline]
 smp_apic_timer_interrupt+0x186/0x730 arch/x86/kernel/apic/apic.c:1055
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
RIP: 0010:__kernel_text_address+0x29/0x40 kernel/extable.c:120
Code: 00 55 48 89 e5 53 48 89 fb e8 03 ff ff ff 85 c0 75 18 48 81 fb 00 30 93 88 72 0c 31 c0 48 81 fb 21 82 ac 88 0f 92 c0 5b 5d c3 <b8> 01 00 00 00 5b 5d c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 
RSP: 0018:ffff8801a0886d18 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: ffffffff81b99a9e RCX: 0000000000000000
RDX: 1ffff10034110db3 RSI: ffff8801a0887078 RDI: ffffffff81b99a9e
RBP: ffff8801a0886d20 R08: ffff8801a0886d88 R09: ffff8801a087e4c0
R10: ffffed0034110db4 R11: ffff8801a0886da7 R12: ffff8801a0886d98
R13: 0000000000000000 R14: ffff8801a087e4c0 R15: ffff8801ab3cb04f
 unwind_get_return_address+0x61/0xa0 arch/x86/kernel/unwind_frame.c:18
 __save_stack_trace+0x8d/0xf0 arch/x86/kernel/stacktrace.c:45
 save_stack_trace+0x1a/0x20 arch/x86/kernel/stacktrace.c:60
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 alloc_pid+0xc9/0xa70 kernel/pid.c:168
 copy_process.part.39+0x2f96/0x70b0 kernel/fork.c:1840
 copy_process kernel/fork.c:1639 [inline]
 _do_fork+0x291/0x12a0 kernel/fork.c:2122
 __do_sys_clone kernel/fork.c:2229 [inline]
 __se_sys_clone kernel/fork.c:2223 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2223
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4550ba
Code: f7 d8 64 89 04 25 d4 02 00 00 64 4c 8b 0c 25 10 00 00 00 31 d2 4d 8d 91 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 f5 00 00 00 85 c0 41 89 c5 0f 85 fc 00 00 
RSP: 002b:00007ffe303be820 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffe303be820 RCX: 00000000004550ba
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffe303be860 R08: 0000000000000001 R09: 0000000002889940
R10: 0000000002889c10 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: badc0ffeebadface

Allocated by task 9553:
 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:2347
 inet6_addr_modify net/ipv6/addrconf.c:4627 [inline]
 inet6_rtm_newaddr+0x112e/0x1b50 net/ipv6/addrconf.c:4743
 rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4665
 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2453
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4683
 netlink_unicast_kernel net/netlink/af_netlink.c:1315 [inline]
 netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1341
 netlink_sendmsg+0xa18/0xfd0 net/netlink/af_netlink.c:1906
 sock_sendmsg_nosec net/socket.c:642 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:652
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2126
 __sys_sendmsg+0x11d/0x290 net/socket.c:2164
 __do_sys_sendmsg net/socket.c:2173 [inline]
 __se_sys_sendmsg net/socket.c:2171 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2171
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4433:
 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 net/ipv6/ip6_fib.c:2051 [inline]
 fib6_run_gc+0x182/0x3d0 net/ipv6/ip6_fib.c:2107
 fib6_gc_timer_cb+0x20/0x30 net/ipv6/ip6_fib.c:2124
 call_timer_fn+0x242/0x970 kernel/time/timer.c:1326
 expire_timers kernel/time/timer.c:1363 [inline]
 __run_timers+0x7a6/0xc70 kernel/time/timer.c:1666
 run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
 __do_softirq+0x2e8/0xb17 kernel/softirq.c:292

The buggy address belongs to the object at ffff8801c7aec580
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
 96-byte region [ffff8801c7aec580, ffff8801c7aec5e0)
The buggy address belongs to the page:
page:ffffea00071ebb00 count:1 mapcount:0 mapping:ffff8801dac004c0 index:0xffff8801c7aecd80
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0006aa0e88 ffffea0006ac5bc8 ffff8801dac004c0
raw: ffff8801c7aecd80 ffff8801c7aec000 000000010000001f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c7aec480: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff8801c7aec500: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8801c7aec580: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                   ^
 ffff8801c7aec600: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff8801c7aec680: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
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