==================================================================
BUG: KASAN: use-after-free in decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3393
Read of size 1 at addr ffff88806c0728af by task syz-executor.4/29269

CPU: 0 PID: 29269 Comm: syz-executor.4 Not tainted 5.10.0-rc2-next-20201105-syzkaller #0
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+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3393
 __xfrm_decode_session net/xfrm/xfrm_policy.c:3485 [inline]
 __xfrm_policy_check+0x2fa/0x2850 net/xfrm/xfrm_policy.c:3540
 __xfrm_policy_check2 include/net/xfrm.h:1097 [inline]
 xfrm_policy_check include/net/xfrm.h:1106 [inline]
 sctp_rcv+0x12b0/0x2e30 net/sctp/input.c:202
 sctp6_rcv+0x22/0x40 net/sctp/ipv6.c:1078
 ip6_protocol_deliver_rcu+0x2e8/0x1680 net/ipv6/ip6_input.c:433
 ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
 NF_HOOK include/linux/netfilter.h:301 [inline]
 NF_HOOK include/linux/netfilter.h:295 [inline]
 ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
 dst_input include/net/dst.h:447 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 NF_HOOK include/linux/netfilter.h:295 [inline]
 ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5315
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5429
 process_backlog+0x232/0x6c0 net/core/dev.c:6319
 napi_poll net/core/dev.c:6763 [inline]
 net_rx_action+0x4dc/0x1100 net/core/dev.c:6833
 __do_softirq+0x2a0/0x9f6 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77
 do_softirq kernel/softirq.c:343 [inline]
 do_softirq+0xb5/0xe0 kernel/softirq.c:330
 __local_bh_enable_ip+0xf0/0x110 kernel/softirq.c:195
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:731 [inline]
 ip6_finish_output2+0x71f/0x16c0 net/ipv6/ip6_output.c:118
 __ip6_finish_output net/ipv6/ip6_output.c:143 [inline]
 __ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128
 ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
 NF_HOOK_COND include/linux/netfilter.h:290 [inline]
 ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176
 dst_output include/net/dst.h:441 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 NF_HOOK include/linux/netfilter.h:295 [inline]
 ip6_xmit+0x1258/0x1e80 net/ipv6/ip6_output.c:280
 sctp_v6_xmit+0xbf3/0xfe0 net/sctp/ipv6.c:223
 sctp_packet_transmit+0x1f44/0x32f0 net/sctp/output.c:627
 sctp_packet_singleton net/sctp/outqueue.c:773 [inline]
 sctp_outq_flush_ctrl.constprop.0+0x6d3/0xc40 net/sctp/outqueue.c:904
 sctp_outq_flush+0xf3/0x2580 net/sctp/outqueue.c:1186
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1314 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
 sctp_do_sm+0x3c93/0x5120 net/sctp/sm_sideeffect.c:1156
 sctp_assoc_bh_rcv+0x386/0x6c0 net/sctp/associola.c:1048
 sctp_inq_push+0x1da/0x270 net/sctp/inqueue.c:80
 sctp_backlog_rcv+0x19e/0x5c0 net/sctp/input.c:344
 sk_backlog_rcv include/net/sock.h:1010 [inline]
 __release_sock+0x134/0x3a0 net/core/sock.c:2523
 release_sock+0x54/0x1b0 net/core/sock.c:3053
 sctp_connect net/sctp/socket.c:4732 [inline]
 sctp_inet_connect+0x16e/0x200 net/sctp/socket.c:4745
 __sys_connect_file+0x155/0x1a0 net/socket.c:1852
 __sys_connect+0x161/0x190 net/socket.c:1869
 __do_sys_connect net/socket.c:1879 [inline]
 __se_sys_connect net/socket.c:1876 [inline]
 __x64_sys_connect+0x6f/0xb0 net/socket.c:1876
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45deb9
Code: 0d b4 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 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1264a71c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000002400 RCX: 000000000045deb9
RDX: 000000000000001c RSI: 0000000020000080 RDI: 0000000000000005
RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffede343b3f R14: 00007f1264a729c0 R15: 000000000118bf2c

Allocated by task 29221:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:49
 kasan_set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:480
 slab_post_alloc_hook mm/slab.h:506 [inline]
 slab_alloc_node mm/slub.c:2901 [inline]
 slab_alloc mm/slub.c:2909 [inline]
 kmem_cache_alloc+0x12a/0x470 mm/slub.c:2914
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
 getname_flags+0x9a/0xe0 include/linux/audit.h:319
 getname fs/namei.c:209 [inline]
 __do_sys_rename fs/namei.c:4511 [inline]
 __se_sys_rename fs/namei.c:4509 [inline]
 __x64_sys_rename+0x56/0xa0 fs/namei.c:4509
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 29221:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:49
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:57
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:356
 __kasan_slab_free+0x102/0x140 mm/kasan/common.c:438
 slab_free_hook mm/slub.c:1545 [inline]
 slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1583
 slab_free mm/slub.c:3155 [inline]
 kmem_cache_free+0x82/0x350 mm/slub.c:3171
 putname+0xe1/0x120 fs/namei.c:259
 do_renameat2+0x244/0xc20 fs/namei.c:4476
 __do_sys_rename fs/namei.c:4511 [inline]
 __se_sys_rename fs/namei.c:4509 [inline]
 __x64_sys_rename+0x7d/0xa0 fs/namei.c:4509
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88806c072200
 which belongs to the cache names_cache of size 4096
The buggy address is located 1711 bytes inside of
 4096-byte region [ffff88806c072200, ffff88806c073200)
The buggy address belongs to the page:
page:000000002a756893 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6c070
head:000000002a756893 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff8880101c2280
raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88806c072780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806c072800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88806c072880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88806c072900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806c072980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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