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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 24 at addr ffff8801af1293b8 by task syz-executor1/15986

CPU: 0 PID: 15986 Comm: syz-executor1 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
netlink: 'syz-executor3': attribute type 21 has an invalid length.
 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:00007f1a81e43c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007f1a81e446d4 RCX: 0000000000456cb9
RDX: 0000000020000740 RSI: 0000000020000000 RDI: 0000000000000017
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000084 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d1920 R14: 00000000004c72f5 R15: 0000000000000000

Allocated by task 15986:
 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 6368:
 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
 ep_free+0x269/0x300 fs/eventpoll.c:861
 ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:869
 __fput+0x376/0x8a0 fs/file_table.c:279
 ____fput+0x15/0x20 fs/file_table.c:312
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801af129280
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 312 bytes inside of
 512-byte region [ffff8801af129280, ffff8801af129480)
The buggy address belongs to the page:
page:ffffea0006bc4a40 count:1 mapcount:0 mapping:ffff8801dac00940 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0006bf4ac8 ffffea0006cd2908 ffff8801dac00940
raw: 0000000000000000 ffff8801af129000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801af129280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801af129300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801af129380: 00 00 00 00 00 00 00 00 00 04 fc fc fc fc fc fc
                                              ^
 ffff8801af129400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801af129480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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