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BUG: KASAN: slab-out-of-bounds in sctp_send_reset_streams+0xb03/0xc10 net/sctp/stream.c:323
Read of size 2 at addr ffff8801c520fd48 by task syzkaller678996/3154

CPU: 1 PID: 3154 Comm: syzkaller678996 Not tainted 4.15.0-rc2-next-20171208+ #63
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:428
 sctp_send_reset_streams+0xb03/0xc10 net/sctp/stream.c:323
 sctp_setsockopt_reset_streams net/sctp/socket.c:3905 [inline]
 sctp_setsockopt+0x70d/0x5d50 net/sctp/socket.c:4195
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2968
 SYSC_setsockopt net/socket.c:1829 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1808
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x445629
RSP: 002b:00007f022a676dc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445629
RDX: 0000000000000077 RSI: 0000000000000084 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000008 R09: 00007f022a677700
R10: 0000000020b24000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffc97534bdf R14: 00007f022a6779c0 R15: 0000000000000000

Allocated by task 3154:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3712 [inline]
 __kmalloc_track_caller+0x15e/0x760 mm/slab.c:3727
 memdup_user+0x2c/0x90 mm/util.c:164
 sctp_setsockopt_reset_streams net/sctp/socket.c:3897 [inline]
 sctp_setsockopt+0x6a6/0x5d50 net/sctp/socket.c:4195
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2968
 SYSC_setsockopt net/socket.c:1829 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1808
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 1637:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3492 [inline]
 kfree+0xca/0x250 mm/slab.c:3807
 selinux_sk_free_security+0x4f/0x60 security/selinux/hooks.c:4909
 security_sk_free+0x48/0x80 security/security.c:1431
 sk_prot_free net/core/sock.c:1502 [inline]
 __sk_destruct+0x609/0x910 net/core/sock.c:1585
 sk_destruct+0x47/0x80 net/core/sock.c:1593
 __sk_free+0x57/0x230 net/core/sock.c:1601
 sk_free+0x2a/0x40 net/core/sock.c:1612
 sock_put include/net/sock.h:1653 [inline]
 unix_release_sock+0x644/0xc10 net/unix/af_unix.c:566
 unix_release+0x44/0x90 net/unix/af_unix.c:838
 sock_release+0x8d/0x1e0 net/socket.c:600
 sock_close+0x16/0x20 net/socket.c:1129
 __fput+0x333/0x7f0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x94/0x96

The buggy address belongs to the object at ffff8801c520fd40
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 8 bytes inside of
 32-byte region [ffff8801c520fd40, ffff8801c520fd60)
The buggy address belongs to the page:
page:00000000c753f0c9 count:1 mapcount:0 mapping:000000000af62544 index:0xffff8801c520ffc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c520f000 ffff8801c520ffc1 000000010000003f
raw: ffffea0007153ce0 ffffea00071488a0 ffff8801dac001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c520fc00: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
 ffff8801c520fc80: fb fb fb fb fc fc fc fc 00 00 04 fc fc fc fc fc
>ffff8801c520fd00: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc
                                              ^
 ffff8801c520fd80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801c520fe00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
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