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BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:147 [inline]
BUG: KASAN: use-after-free in ip6_fragment+0x2d4a/0x2f30 net/ipv6/ip6_output.c:768
Read of size 8 at addr ffff8881c3956318 by task syz-executor.1/6766

CPU: 1 PID: 6766 Comm: syz-executor.1 Not tainted 4.14.139+ #34
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 ip6_dst_idev include/net/ip6_fib.h:147 [inline]
 ip6_fragment+0x2d4a/0x2f30 net/ipv6/ip6_output.c:768
 ip6_finish_output+0x66d/0xb40 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip6_output+0x1dc/0x680 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:462 [inline]
 ip6_local_out+0x98/0x170 net/ipv6/output_core.c:178
 ip6_send_skb+0x9b/0x2f0 net/ipv6/ip6_output.c:1688
 udp_v6_send_skb+0x4e2/0xe80 net/ipv6/udp.c:1081
 udp_v6_push_pending_frames+0x224/0x330 net/ipv6/udp.c:1114
 udpv6_sendmsg+0x194b/0x2500 net/ipv6/udp.c:1380
 inet_sendmsg+0x15b/0x520 net/ipv4/af_inet.c:760
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 sock_write_iter+0x20f/0x360 net/socket.c:925
 call_write_iter include/linux/fs.h:1788 [inline]
 new_sync_write fs/read_write.c:471 [inline]
 __vfs_write+0x401/0x5a0 fs/read_write.c:484
 vfs_write+0x17f/0x4d0 fs/read_write.c:546
 SYSC_write fs/read_write.c:594 [inline]
 SyS_write+0x102/0x250 fs/read_write.c:586
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459829
RSP: 002b:00007fc204dbfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 000000000000ffdc RSI: 0000000020000200 RDI: 0000000000000004
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc204dc06d4
R13: 00000000004c995e R14: 00000000004e0fc8 R15: 00000000ffffffff

Allocated by task 6286:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc.part.0+0x53/0xc0 mm/kasan/common.c:495
 slab_post_alloc_hook mm/slab.h:439 [inline]
 slab_alloc_node mm/slub.c:2758 [inline]
 slab_alloc mm/slub.c:2766 [inline]
 kmem_cache_alloc+0xd2/0x2e0 mm/slub.c:2771
 dst_alloc+0xe6/0x1a0 net/core/dst.c:107
 __ip6_dst_alloc+0x2e/0x50 net/ipv6/route.c:355
 ip6_rt_pcpu_alloc net/ipv6/route.c:1034 [inline]
 rt6_make_pcpu_route net/ipv6/route.c:1064 [inline]
 ip6_pol_route+0xfed/0x26d0 net/ipv6/route.c:1189
 fib6_rule_lookup+0x1e9/0x420 net/ipv6/fib6_rules.c:87
 ip6_dst_lookup_tail+0x3ec/0x16f0 net/ipv6/ip6_output.c:997
 ip6_dst_lookup_flow+0xac/0x210 net/ipv6/ip6_output.c:1098
 inet6_csk_route_socket+0x743/0xbd0 net/ipv6/inet6_connection_sock.c:110
 inet6_csk_xmit+0xff/0x500 net/ipv6/inet6_connection_sock.c:125
 __tcp_transmit_skb+0x18bc/0x2e20 net/ipv4/tcp_output.c:1130
 tcp_transmit_skb net/ipv4/tcp_output.c:1146 [inline]
 tcp_write_xmit+0x510/0x4680 net/ipv4/tcp_output.c:2381
 __tcp_push_pending_frames+0xa0/0x230 net/ipv4/tcp_output.c:2562
 tcp_push+0x402/0x600 net/ipv4/tcp.c:715
 tcp_sendmsg_locked+0x124f/0x31e0 net/ipv4/tcp.c:1396
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1446
 inet_sendmsg+0x15b/0x520 net/ipv4/af_inet.c:760
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 SYSC_sendto net/socket.c:1763 [inline]
 SyS_sendto+0x1de/0x2f0 net/socket.c:1731
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

Freed by task 7:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x164/0x210 mm/kasan/common.c:457
 slab_free_hook mm/slub.c:1403 [inline]
 slab_free_freelist_hook mm/slub.c:1430 [inline]
 slab_free mm/slub.c:3005 [inline]
 kmem_cache_free+0xcb/0x340 mm/slub.c:3021
 dst_destroy+0x1cc/0x2d0 net/core/dst.c:138
 __rcu_reclaim kernel/rcu/rcu.h:195 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x59f/0xf60 kernel/rcu/tree.c:2946
 __do_softirq+0x234/0x9ec kernel/softirq.c:288

The buggy address belongs to the object at ffff8881c39561c0
 which belongs to the cache ip6_dst_cache of size 384
The buggy address is located 344 bytes inside of
 384-byte region [ffff8881c39561c0, ffff8881c3956340)
The buggy address belongs to the page:
page:ffffea00070e5580 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 0000000000000000 0000000000000000 0000000100120012
raw: ffffea00072da000 0000000b0000000b ffff8881d5da5c00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c3956200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881c3956280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881c3956300: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff8881c3956380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881c3956400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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