==================================================================
BUG: KASAN: slab-out-of-bounds in fl6_update_dst+0x2bb/0x2c0 net/ipv6/exthdrs.c:1356
Read of size 16 at addr ffff88805a6fd0c8 by task syz-executor.0/1386

CPU: 1 PID: 1386 Comm: syz-executor.0 Not tainted 5.7.0-rc4-syzkaller #0
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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382
 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 fl6_update_dst+0x2bb/0x2c0 net/ipv6/exthdrs.c:1356
 udpv6_sendmsg+0x1866/0x2b50 net/ipv6/udp.c:1431
 inet6_sendmsg+0x99/0xe0 net/ipv6/af_inet6.c:577
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x308/0x7e0 net/socket.c:2362
 ___sys_sendmsg+0x100/0x170 net/socket.c:2416
 __sys_sendmmsg+0x195/0x480 net/socket.c:2506
 __do_sys_sendmmsg net/socket.c:2535 [inline]
 __se_sys_sendmmsg net/socket.c:2532 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2532
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f454e685c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004fc320 RCX: 000000000045c829
RDX: 00000000000000c6 RSI: 0000000020006d00 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008dd R14: 00000000004cb81f R15: 00007f454e6866d4

Allocated by task 1386:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x161/0x7a0 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 sock_kmalloc net/core/sock.c:2166 [inline]
 sock_kmalloc+0xb5/0x100 net/core/sock.c:2157
 ipv6_renew_options+0x274/0x940 net/ipv6/exthdrs.c:1275
 do_ipv6_setsockopt.isra.0+0x2eaf/0x42f0 net/ipv6/ipv6_sockglue.c:435
 ipv6_setsockopt+0xfb/0x180 net/ipv6/ipv6_sockglue.c:949
 udpv6_setsockopt+0x5d/0xa0 net/ipv6/udp.c:1567
 __sys_setsockopt+0x248/0x480 net/socket.c:2132
 __do_sys_setsockopt net/socket.c:2148 [inline]
 __se_sys_setsockopt net/socket.c:2145 [inline]
 __x64_sys_setsockopt+0xba/0x150 net/socket.c:2145
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 311:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 tc_action_net_exit include/net/act_api.h:151 [inline]
 csum_exit_net+0x185/0x360 net/sched/act_csum.c:722
 ops_exit_list.isra.0+0x103/0x150 net/core/net_namespace.c:189
 cleanup_net+0x511/0xa50 net/core/net_namespace.c:603
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88805a6fd000
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 200 bytes inside of
 256-byte region [ffff88805a6fd000, ffff88805a6fd100)
The buggy address belongs to the page:
page:ffffea000169bf40 refcount:1 mapcount:0 mapping:00000000301a5e1c index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029c4ac8 ffffea0002261548 ffff8880aa0008c0
raw: 0000000000000000 ffff88805a6fd000 0000000100000008 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805a6fcf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805a6fd000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805a6fd080: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
                                              ^
 ffff88805a6fd100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805a6fd180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================