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BUG: KASAN: slab-out-of-bounds in ip6_dst_lookup_tail+0x196a/0x1b30 net/ipv6/ip6_output.c:1010
Read of size 8 at addr ffff888093085b7f by task syz-executor.1/24127

CPU: 1 PID: 24127 Comm: syz-executor.1 Not tainted 5.2.0-rc1+ #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __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:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 ip6_dst_lookup_tail+0x196a/0x1b30 net/ipv6/ip6_output.c:1010
 ip6_dst_lookup_flow+0xa8/0x220 net/ipv6/ip6_output.c:1094
 inet6_csk_route_socket+0x85d/0xf40 net/ipv6/inet6_connection_sock.c:110
 inet6_csk_xmit+0x110/0x5d0 net/ipv6/inet6_connection_sock.c:125
 l2tp_xmit_core net/l2tp/l2tp_core.c:1033 [inline]
 l2tp_xmit_skb+0x1112/0x13e0 net/l2tp/l2tp_core.c:1135
 pppol2tp_sendmsg+0x4a2/0x6b0 net/l2tp/l2tp_ppp.c:329
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2292
 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2387
 __do_sys_sendmmsg net/socket.c:2416 [inline]
 __se_sys_sendmmsg net/socket.c:2413 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2413
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f26f242fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459279
RDX: 0800000000000198 RSI: 0000000020005fc0 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000c0fe R11: 0000000000000246 R12: 00007f26f24306d4
R13: 00000000004c65fc R14: 00000000004db280 R15: 00000000ffffffff

Allocated by task 17:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
 slab_post_alloc_hook mm/slab.h:437 [inline]
 slab_alloc mm/slab.c:3326 [inline]
 kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3488
 dst_alloc+0x10e/0x200 net/core/dst.c:93
 ip6_dst_alloc+0x34/0xa0 net/ipv6/route.c:356
 icmp6_dst_alloc+0x1a9/0x660 net/ipv6/route.c:2800
 ndisc_send_skb+0xfc1/0x14a0 net/ipv6/ndisc.c:488
 ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:650
 rt6_probe_deferred+0xe3/0x1a0 net/ipv6/route.c:543
 process_one_work+0x989/0x1790 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x354/0x420 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 16:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3698
 dst_destroy+0x29e/0x3c0 net/core/dst.c:129
 dst_destroy_rcu+0x16/0x19 net/core/dst.c:142
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2092 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
 rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
 __do_softirq+0x25c/0x94c kernel/softirq.c:293

The buggy address belongs to the object at ffff888093085a40
 which belongs to the cache ip6_dst_cache of size 224
The buggy address is located 95 bytes to the right of
 224-byte region [ffff888093085a40, ffff888093085b20)
The buggy address belongs to the page:
page:ffffea00024c2140 refcount:1 mapcount:0 mapping:ffff88821645c6c0 index:0xffff8880930857c0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00029f0c48 ffffea00026b3008 ffff88821645c6c0
raw: ffff8880930857c0 ffff888093085040 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888093085a00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff888093085a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888093085b00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff888093085b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888093085c00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
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