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BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:345 [inline]
BUG: KASAN: slab-out-of-bounds in dh_pack_data crypto/dh_helper.c:21 [inline]
BUG: KASAN: slab-out-of-bounds in crypto_dh_encode_key+0x609/0x830 crypto/dh_helper.c:62
Write of size 2 at addr ffff8801ac8bfdd6 by task syz-executor4/14661

CPU: 1 PID: 14661 Comm: syz-executor4 Not tainted 4.18.0-rc7-next-20180803+ #31
netlink: 20 bytes leftover after parsing attributes in process `syz-executor1'.
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+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x37/0x50 mm/kasan/kasan.c:303
 memcpy include/linux/string.h:345 [inline]
 dh_pack_data crypto/dh_helper.c:21 [inline]
 crypto_dh_encode_key+0x609/0x830 crypto/dh_helper.c:62
 __keyctl_dh_compute+0x707/0x1c00 security/keys/dh.c:316
 keyctl_dh_compute+0xc5/0x11f security/keys/dh.c:427
 __do_sys_keyctl security/keys/keyctl.c:1741 [inline]
 __se_sys_keyctl security/keys/keyctl.c:1637 [inline]
 __x64_sys_keyctl+0x12a/0x3b0 security/keys/keyctl.c:1637
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x456cb9
Code: fd 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff05c3f7c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007ff05c3f86d4 RCX: 0000000000456cb9
RDX: 00000000200000c0 RSI: 0000000020000080 RDI: 0000000000000017
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000001000002be R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d1920 R14: 00000000004c72f5 R15: 0000000000000000

Allocated by task 14661:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc+0x14e/0x760 mm/slab.c:3727
 kmalloc include/linux/slab.h:518 [inline]
 __keyctl_dh_compute+0x6e1/0x1c00 security/keys/dh.c:311
 keyctl_dh_compute+0xc5/0x11f security/keys/dh.c:427
 __do_sys_keyctl security/keys/keyctl.c:1741 [inline]
 __se_sys_keyctl security/keys/keyctl.c:1637 [inline]
 __x64_sys_keyctl+0x12a/0x3b0 security/keys/keyctl.c:1637
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4310:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 kvfree+0x61/0x70 mm/util.c:449
 xt_free_table_info+0x115/0x180 net/netfilter/x_tables.c:1203
 __do_replace+0x86f/0xad0 net/ipv6/netfilter/ip6_tables.c:1107
 do_replace net/ipv6/netfilter/ip6_tables.c:1160 [inline]
 do_ip6t_set_ctl+0x49c/0x64b net/ipv6/netfilter/ip6_tables.c:1684
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x7d/0xd0 net/netfilter/nf_sockopt.c:115
 ipv6_setsockopt+0x105/0x170 net/ipv6/ipv6_sockglue.c:938
 tcp_setsockopt+0x93/0xe0 net/ipv4/tcp.c:3063
 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3083
 __sys_setsockopt+0x1c5/0x3b0 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+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801ac8bfdc0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 22 bytes inside of
 32-byte region [ffff8801ac8bfdc0, ffff8801ac8bfde0)
The buggy address belongs to the page:
page:ffffea0006b22fc0 count:1 mapcount:0 mapping:ffff8801dac001c0 index:0xffff8801ac8bffc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00075f6d08 ffffea0006f6b648 ffff8801dac001c0
raw: ffff8801ac8bffc1 ffff8801ac8bf000 0000000100000028 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ac8bfc80: fb fb fb fb fc fc fc fc 05 fc fc fc fc fc fc fc
 ffff8801ac8bfd00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801ac8bfd80: 05 fc fc fc fc fc fc fc 00 00 06 fc fc fc fc fc
                                                 ^
netlink: 20 bytes leftover after parsing attributes in process `syz-executor1'.
 ffff8801ac8bfe00: 00 00 00 fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801ac8bfe80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
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