==================================================================
BUG: KASAN: use-after-free in rt_cache_valid+0x158/0x190 net/ipv4/route.c:1525
Read of size 2 at addr ffff88807de0166a by task syz-executor.4/3163

CPU: 0 PID: 3163 Comm: syz-executor.4 Not tainted 4.19.34 #2
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:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431
 rt_cache_valid+0x158/0x190 net/ipv4/route.c:1525
 __mkroute_output net/ipv4/route.c:2279 [inline]
 ip_route_output_key_hash_rcu+0x89d/0x30e0 net/ipv4/route.c:2511
 ip_route_output_key_hash+0x212/0x380 net/ipv4/route.c:2340
 __ip_route_output_key include/net/route.h:124 [inline]
 ip_route_output_flow+0x28/0xc0 net/ipv4/route.c:2595
 ip_route_output_key include/net/route.h:134 [inline]
 sctp_v4_get_dst+0x467/0x1260 net/sctp/protocol.c:450
 sctp_transport_route+0x132/0x370 net/sctp/transport.c:311
 sctp_assoc_add_peer+0x53e/0xfc0 net/sctp/associola.c:676
 sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
 sctp_process_init+0x24a7/0x2b30 net/sctp/sm_make_chunk.c:2361
 sctp_sf_do_5_1D_ce+0x467/0x13a0 net/sctp/sm_statefuns.c:782
 sctp_do_sm+0x124/0x53a0 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+0x27bd/0x3400 net/sctp/input.c:268
 sctp6_rcv+0x17/0x30 net/sctp/ipv6.c:1060
 ip6_input_finish+0x374/0x1810 net/ipv6/ip6_input.c:383
 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:426
 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+0x119/0x430 net/ipv6/ip6_input.c:271
 __netif_receive_skb_one_core+0x115/0x1a0 net/core/dev.c:4918
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5028
 process_backlog+0x206/0x750 net/core/dev.c:5839
 napi_poll net/core/dev.c:6262 [inline]
 net_rx_action+0x4fa/0x1070 net/core/dev.c:6328
 __do_softirq+0x266/0x92f kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1051
 </IRQ>
 do_softirq.part.0+0x11a/0x170 kernel/softirq.c:336
 do_softirq kernel/softirq.c:328 [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:723 [inline]
 ip6_finish_output2+0xbcf/0x2560 net/ipv6/ip6_output.c:121
 ip6_finish_output+0x580/0xc40 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+0xe50/0x2110 net/ipv6/ip6_output.c:275
 sctp_v6_xmit+0x340/0x690 net/sctp/ipv6.c:229
 sctp_packet_transmit+0x1b26/0x36a0 net/sctp/output.c:659
 sctp_outq_flush_transports net/sctp/outqueue.c:1165 [inline]
 sctp_outq_flush+0x2b8/0x27a0 net/sctp/outqueue.c:1213
 sctp_outq_uncork+0x6c/0x80 net/sctp/outqueue.c:776
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1820 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
 sctp_do_sm+0x51c/0x53a0 net/sctp/sm_sideeffect.c:1191
 sctp_assoc_bh_rcv+0x343/0x660 net/sctp/associola.c:1072
 sctp_inq_push+0x1ea/0x290 net/sctp/inqueue.c:95
 sctp_backlog_rcv+0x189/0xbd0 net/sctp/input.c:351
 sk_backlog_rcv include/net/sock.h:941 [inline]
 __release_sock+0x12e/0x3a0 net/core/sock.c:2337
 release_sock+0x59/0x1c0 net/core/sock.c:2853
 sctp_wait_for_connect+0x316/0x540 net/sctp/socket.c:8654
 __sctp_connect+0xac2/0xce0 net/sctp/socket.c:1259
 __sctp_setsockopt_connectx+0x133/0x1a0 net/sctp/socket.c:1367
 sctp_setsockopt_connectx_old net/sctp/socket.c:1383 [inline]
 sctp_setsockopt net/sctp/socket.c:4338 [inline]
 sctp_setsockopt+0x2bf9/0x4f80 net/sctp/socket.c:4302
 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3044
 __sys_setsockopt+0x180/0x280 net/socket.c:1901
 __do_sys_setsockopt net/socket.c:1912 [inline]
 __se_sys_setsockopt net/socket.c:1909 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1909
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c29
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:00007f09b32c7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458c29
RDX: 000000000000006b RSI: 0000000000000084 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 000000000000001c R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000246 R12: 00007f09b32c86d4
R13: 00000000004ce088 R14: 00000000004dc200 R15: 00000000ffffffff

Allocated by task 8030:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x700 mm/slab.c:3559
 kmem_cache_zalloc include/linux/slab.h:699 [inline]
 copy_signal kernel/fork.c:1477 [inline]
 copy_process.part.0+0x212e/0x7970 kernel/fork.c:1864
 copy_process kernel/fork.c:1664 [inline]
 _do_fork+0x257/0xfe0 kernel/fork.c:2175
 __do_sys_clone kernel/fork.c:2282 [inline]
 __se_sys_clone kernel/fork.c:2276 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2276
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3765
 free_signal_struct kernel/fork.c:666 [inline]
 put_signal_struct kernel/fork.c:672 [inline]
 __put_task_struct+0x2f1/0x4e0 kernel/fork.c:686
 put_task_struct include/linux/sched/task.h:96 [inline]
 delayed_put_task_struct+0x1fd/0x350 kernel/exit.c:181
 __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
 rcu_do_batch kernel/rcu/tree.c:2584 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
 rcu_process_callbacks+0xba9/0x1a40 kernel/rcu/tree.c:2881
 __do_softirq+0x266/0x92f kernel/softirq.c:292

The buggy address belongs to the object at ffff88807de01280
 which belongs to the cache signal_cache(17:syz0) of size 1328
The buggy address is located 1002 bytes inside of
 1328-byte region [ffff88807de01280, ffff88807de017b0)
The buggy address belongs to the page:
page:ffffea0001f78000 count:1 mapcount:0 mapping:ffff888061762000 index:0xffff88807de01280 compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffffea0001553088 ffffea0001726808 ffff888061762000
raw: ffff88807de01280 ffff88807de00140 0000000100000004 ffff888061770500
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888061770500

Memory state around the buggy address:
 ffff88807de01500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807de01580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807de01600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff88807de01680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807de01700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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