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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+0x80e/0x830 crypto/dh_helper.c:60
Write of size 4 at addr ffff8801d57ace50 by task syz-executor3/6802

CPU: 0 PID: 6802 Comm: syz-executor3 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
 __asan_report_store_n_noabort+0x12/0x14 mm/kasan/report.c:449
 memcpy include/linux/string.h:345 [inline]
 dh_pack_data crypto/dh_helper.c:21 [inline]
 crypto_dh_encode_key+0x80e/0x830 crypto/dh_helper.c:60
 __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: 0033:0x456b29
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:00007f54eb9dec78 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007f54eb9df6d4 RCX: 0000000000456b29
RDX: 0000000020000280 RSI: 0000000020000200 RDI: 0000000000000017
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0e736a4920f22c0a R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d16a0 R14: 00000000004c7069 R15: 0000000000000000

Allocated by task 6802:
 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 2186:
 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
 __vunmap+0x326/0x460 mm/vmalloc.c:1529
 vfree+0x68/0x100 mm/vmalloc.c:1593
 n_tty_close+0xc3/0x130 drivers/tty/n_tty.c:1880
 tty_ldisc_close.isra.0+0xb0/0xe0 drivers/tty/tty_ldisc.c:477
 tty_ldisc_kill+0x4b/0xc0 drivers/tty/tty_ldisc.c:623
 tty_ldisc_hangup+0x2dd/0x640 drivers/tty/tty_ldisc.c:741
 __tty_hangup.part.21+0x2da/0x6e0 drivers/tty/tty_io.c:621
 __tty_hangup drivers/tty/tty_io.c:571 [inline]
 tty_vhangup+0x21/0x30 drivers/tty/tty_io.c:694
 pty_close+0x3bd/0x510 drivers/tty/pty.c:78
 tty_release+0x4b3/0x1300 drivers/tty/tty_io.c:1656
 __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 ffff8801d57ace40
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 16 bytes inside of
 32-byte region [ffff8801d57ace40, ffff8801d57ace60)
The buggy address belongs to the page:
page:ffffea000755eb00 count:1 mapcount:0 mapping:ffff8801dac001c0 index:0xffff8801d57acfc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea000755e748 ffffea00075a3788 ffff8801dac001c0
raw: ffff8801d57acfc1 ffff8801d57ac000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d57acd00: 05 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d57acd80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801d57ace00: fb fb fb fb fc fc fc fc 00 00 03 fc fc fc fc fc
                                                 ^
 ffff8801d57ace80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d57acf00: fb fb fb fb fc fc fc fc 00 00 00 fc fc fc fc fc
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