netlink: 20 bytes leftover after parsing attributes in process `syz-executor.0'.
==================================================================
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in atomic_fetch_add_unless include/linux/atomic.h:575 [inline]
BUG: KASAN: use-after-free in atomic_add_unless include/linux/atomic.h:597 [inline]
BUG: KASAN: use-after-free in dst_hold_safe include/net/dst.h:308 [inline]
BUG: KASAN: use-after-free in ip6_hold_safe+0xa7/0x3a0 net/ipv6/route.c:1023
Read of size 4 at addr ffff8880a01217e0 by task syz-executor.1/22996

CPU: 0 PID: 22996 Comm: syz-executor.1 Not tainted 5.0.0+ #97
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_read+0x11/0x20 mm/kasan/common.c:100
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 atomic_fetch_add_unless include/linux/atomic.h:575 [inline]
 atomic_add_unless include/linux/atomic.h:597 [inline]
 dst_hold_safe include/net/dst.h:308 [inline]
 ip6_hold_safe+0xa7/0x3a0 net/ipv6/route.c:1023
 rt6_get_pcpu_route net/ipv6/route.c:1243 [inline]
 ip6_pol_route+0x33d/0xf00 net/ipv6/route.c:1904
 ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2080
 fib6_rule_lookup+0x128/0x560 net/ipv6/fib6_rules.c:118
 ip6_route_output_flags+0x2c4/0x350 net/ipv6/route.c:2109
 ip6_route_output include/net/ip6_route.h:88 [inline]
 ip6_dst_lookup_tail+0xd10/0x1b30 net/ipv6/ip6_output.c:964
 ip6_dst_lookup_flow+0xa8/0x220 net/ipv6/ip6_output.c:1092
 sctp_v6_get_dst+0x785/0x1d80 net/sctp/ipv6.c:293
 sctp_transport_route+0x132/0x370 net/sctp/transport.c:312
 sctp_assoc_add_peer+0x53e/0xfc0 net/sctp/associola.c:678
 sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
 sctp_process_init+0x249f/0x2b20 net/sctp/sm_make_chunk.c:2361
 sctp_sf_do_5_1B_init+0x8ba/0xe50 net/sctp/sm_statefuns.c:416
 sctp_do_sm+0x124/0x5390 net/sctp/sm_sideeffect.c:1188
 sctp_endpoint_bh_rcv+0x451/0x950 net/sctp/endpointola.c:456
 sctp_inq_push+0x1ea/0x290 net/sctp/inqueue.c:95
 sctp_rcv+0x27d9/0x3550 net/sctp/input.c:271
 sctp6_rcv+0x17/0x30 net/sctp/ipv6.c:1063
 ip6_protocol_deliver_rcu+0x303/0x16c0 net/ipv6/ip6_input.c:394
 ip6_input_finish+0x84/0x170 net/ipv6/ip6_input.c:434
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ip6_input+0xe4/0x3f0 net/ipv6/ip6_input.c:443
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x1e7/0x320 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ipv6_rcv+0x10e/0x420 net/ipv6/ip6_input.c:272
 __netif_receive_skb_one_core+0x115/0x1a0 net/core/dev.c:4973
 __netif_receive_skb+0x2c/0x1c0 net/core/dev.c:5083
 process_backlog+0x206/0x750 net/core/dev.c:5923
 napi_poll net/core/dev.c:6346 [inline]
 net_rx_action+0x4fa/0x1070 net/core/dev.c:6412
 __do_softirq+0x266/0x95a kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1027
 </IRQ>
 do_softirq.part.0+0x11a/0x170 kernel/softirq.c:337
 do_softirq kernel/softirq.c:329 [inline]
 __local_bh_enable_ip+0x211/0x270 kernel/softirq.c:189
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:696 [inline]
 ip6_finish_output2+0xbcf/0x2550 net/ipv6/ip6_output.c:121
 ip6_finish_output+0x577/0xc30 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:444 [inline]
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ip6_xmit+0xe41/0x20c0 net/ipv6/ip6_output.c:275
 sctp_v6_xmit+0x313/0x660 net/sctp/ipv6.c:232
 sctp_packet_transmit+0x1b8b/0x3660 net/sctp/output.c:641
 sctp_packet_singleton net/sctp/outqueue.c:787 [inline]
 sctp_outq_flush_ctrl.constprop.0+0x741/0xd40 net/sctp/outqueue.c:918
 sctp_outq_flush+0xe8/0x2790 net/sctp/outqueue.c:1200
 sctp_outq_uncork+0x6c/0x80 net/sctp/outqueue.c:772
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1820 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
 sctp_do_sm+0x513/0x5390 net/sctp/sm_sideeffect.c:1191
 sctp_primitive_ASSOCIATE+0x9d/0xd0 net/sctp/primitive.c:88
 sctp_sendmsg_to_asoc+0x586/0x17d0 net/sctp/socket.c:1924
 sctp_sendmsg+0x10a9/0x17e0 net/sctp/socket.c:2114
sctp: [Deprecated]: syz-executor.3 (pid 23015) Use of int in maxseg socket option.
Use struct sctp_assoc_value instead
 inet_sendmsg+0x147/0x5d0 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:632
 __sys_sendto+0x262/0x380 net/socket.c:1809
 __do_sys_sendto net/socket.c:1821 [inline]
 __se_sys_sendto net/socket.c:1817 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1817
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457f29
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007feab8b76c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000457f29
RDX: 0000000000000001 RSI: 000000002087dffe RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000020000200 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000246 R12: 00007feab8b776d4
R13: 00000000004c565d R14: 00000000004d95a0 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea0002804840 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 ffffffff02800301 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a0121680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880a0121700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880a0121780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                       ^
 ffff8880a0121800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880a0121880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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