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BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:188 [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 ffff8801c4e38c20 by task syz-executor2/17762

CPU: 1 PID: 17762 Comm: syz-executor2 Not tainted 4.15.0-rc7-mm1+ #53
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:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __read_once_size include/linux/compiler.h:188 [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:1808 [inline]
 SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1782
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452ac9
RSP: 002b:00007f66101b6c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 0000000000000018 RSI: 0000000020593fe8 RDI: 0000000000000001
RBP: 00000000000003aa R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f3890
R13: 00000000ffffffff R14: 00007f66101b76d4 R15: 0000000000000000

Allocated by task 3547:
 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:552
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3607
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:704 [inline]
 seq_open+0x83/0x1f0 fs/seq_file.c:54
 kernfs_fop_open+0x684/0xeb0 fs/kernfs/file.c:704
 do_dentry_open+0x667/0xd40 fs/open.c:752
 vfs_open+0x107/0x220 fs/open.c:866
 do_last fs/namei.c:3397 [inline]
 path_openat+0x1151/0x3530 fs/namei.c:3537
 do_filp_open+0x25b/0x3b0 fs/namei.c:3572
 do_sys_open+0x502/0x6d0 fs/open.c:1059
 SYSC_open fs/open.c:1077 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1072
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 3547:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd9/0x260 mm/slab.c:3800
 seq_release+0x59/0x70 fs/seq_file.c:366
 kernfs_fop_release+0x10b/0x180 fs/kernfs/file.c:781
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 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+0x9e/0xa0

The buggy address belongs to the object at ffff8801c4e38b80
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 160 bytes inside of
 256-byte region [ffff8801c4e38b80, ffff8801c4e38c80)
The buggy address belongs to the page:
page:ffffea0007138e00 count:1 mapcount:0 mapping:ffff8801c4e38040 index:0xffff8801c4e38e00
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c4e38040 ffff8801c4e38e00 0000000100000008
raw: ffffea0006f162a0 ffffea000733d2e0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c4e38b00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c4e38b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801c4e38c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8801c4e38c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801c4e38d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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