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BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:183 [inline]
BUG: KASAN: use-after-free in bpf_fd_array_map_lookup_elem+0x440/0x4c0 kernel/bpf/arraymap.c:374
Read of size 8 at addr ffff8801d039c378 by task syz-executor2/21110

CPU: 1 PID: 21110 Comm: syz-executor2 Not tainted 4.15.0-rc7+ #261
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_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 __read_once_size include/linux/compiler.h:183 [inline]
 bpf_fd_array_map_lookup_elem+0x440/0x4c0 kernel/bpf/arraymap.c:374
 map_lookup_elem+0x6b5/0xbd0 kernel/bpf/syscall.c:577
 SYSC_bpf kernel/bpf/syscall.c:1711 [inline]
 SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1685
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452cf9
RSP: 002b:00007fbc1ba32c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452cf9
RDX: 0000000000000018 RSI: 00000000206d1fe8 RDI: 0000000000000001
RBP: 000000000000025a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f1910
R13: 00000000ffffffff R14: 00007fbc1ba336d4 R15: 0000000000000000

Allocated by task 8560:
 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:3708 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3717
 kmalloc include/linux/slab.h:504 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 new_dir fs/proc/proc_sysctl.c:939 [inline]
 get_subdir fs/proc/proc_sysctl.c:984 [inline]
 __register_sysctl_table+0x91d/0x10b0 fs/proc/proc_sysctl.c:1327
 register_net_sysctl+0x29/0x30 net/sysctl_net.c:120
 __addrconf_sysctl_register+0x21a/0x400 net/ipv6/addrconf.c:6399
 addrconf_init_net+0x219/0x2d0 net/ipv6/addrconf.c:6492
 ops_init+0x10a/0x570 net/core/net_namespace.c:118
 setup_net+0x313/0x710 net/core/net_namespace.c:295
 copy_net_ns+0x27c/0x580 net/core/net_namespace.c:419
 create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
 SYSC_unshare kernel/fork.c:2365 [inline]
 SyS_unshare+0x653/0xfa0 kernel/fork.c:2315
 entry_SYSCALL_64_fastpath+0x23/0x9a

Freed by task 0:
 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:3488 [inline]
 kfree+0xd6/0x260 mm/slab.c:3803
 __rcu_reclaim kernel/rcu/rcu.h:190 [inline]
 rcu_do_batch kernel/rcu/tree.c:2758 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:3012 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2979 [inline]
 rcu_process_callbacks+0xe94/0x17f0 kernel/rcu/tree.c:2996
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801d039c280
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 248 bytes inside of
 256-byte region [ffff8801d039c280, ffff8801d039c380)
The buggy address belongs to the page:
page:ffffea000740e700 count:1 mapcount:0 mapping:ffff8801d039c000 index:0xffff8801d039cdc0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d039c000 ffff8801d039cdc0 0000000100000009
raw: ffffea00070921a0 ffffea0006f33aa0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d039c200: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff8801d039c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801d039c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff8801d039c380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801d039c400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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