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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+0x670/0x830 crypto/dh_helper.c:64
Write of size 843 at addr ffff88019c2a7520 by task syz-executor2/26539

CPU: 1 PID: 26539 Comm: syz-executor2 Not tainted 4.18.0-rc7-next-20180803+ #31
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+0x670/0x830 crypto/dh_helper.c:64
 __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:00007f8904971c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007f89049726d4 RCX: 0000000000456cb9
RDX: 0000000020000600 RSI: 0000000020000340 RDI: 0000000000000017
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffff98 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d1920 R14: 00000000004c72f5 R15: 0000000000000000

Allocated by task 26539:
 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 4349:
 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+0x122/0x180 net/netfilter/x_tables.c:1206
 __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 ffff88019c2a71c0
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 864 bytes inside of
 2048-byte region [ffff88019c2a71c0, ffff88019c2a79c0)
The buggy address belongs to the page:
page:ffffea000670a980 count:1 mapcount:0 mapping:ffff8801dac00c40 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0006ff3e08 ffffea0006d75d88 ffff8801dac00c40
raw: 0000000000000000 ffff88019c2a60c0 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88019c2a7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88019c2a7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88019c2a7800: 00 00 00 00 00 00 00 00 00 00 00 00 07 fc fc fc
                                                       ^
 ffff88019c2a7880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88019c2a7900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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