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BUG: KASAN: slab-out-of-bounds in cap_convert_nscap+0x501/0x610 security/commoncap.c:498
Read of size 4 at addr ffff8801cdb74280 by task syz-executor4/7844

CPU: 1 PID: 7844 Comm: syz-executor4 Not tainted 4.15.0-rc4-next-20171221+ #78
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_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 cap_convert_nscap+0x501/0x610 security/commoncap.c:498
 setxattr+0x365/0x400 fs/xattr.c:446
 SYSC_fsetxattr fs/xattr.c:508 [inline]
 SyS_fsetxattr+0x130/0x190 fs/xattr.c:497
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452ac9
RSP: 002b:00007f75e84c1c58 EFLAGS: 00000212 ORIG_RAX: 00000000000000be
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 00000000208ccffe RSI: 00000000204e9fec RDI: 0000000000000014
RBP: 00000000000003a3 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000212 R12: 00000000006f37e8
R13: 00000000ffffffff R14: 00007f75e84c26d4 R15: 0000000000000000

Allocated by task 7844:
 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_node mm/slab.c:3673 [inline]
 __kmalloc_node+0x47/0x70 mm/slab.c:3680
 kmalloc_node include/linux/slab.h:558 [inline]
 kvmalloc_node+0x99/0xd0 mm/util.c:397
 kvmalloc include/linux/mm.h:541 [inline]
 setxattr+0x152/0x400 fs/xattr.c:435
 SYSC_fsetxattr fs/xattr.c:508 [inline]
 SyS_fsetxattr+0x130/0x190 fs/xattr.c:497
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 4916:
 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:3489 [inline]
 kfree+0xd6/0x260 mm/slab.c:3804
 kvfree+0x36/0x60 mm/util.c:416
 kvm_arch_free_memslot+0x85/0x230 arch/x86/kvm/x86.c:8429
 kvm_free_memslot+0xb8/0x110 arch/x86/kvm/../../../virt/kvm/kvm_main.c:530
 kvm_free_memslots+0x9d/0xd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:543
 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:731 [inline]
 kvm_put_kvm+0x916/0xde0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:749
 kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:760
 __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
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:869
 do_group_exit+0x149/0x400 kernel/exit.c:972
 get_signal+0x73f/0x16c0 kernel/signal.c:2337
 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:161
 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 ffff8801cdb74280
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8801cdb74280, ffff8801cdb742a0)
The buggy address belongs to the page:
page:00000000885b00b6 count:1 mapcount:0 mapping:00000000116a97f4 index:0xffff8801cdb74fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801cdb74000 ffff8801cdb74fc1 0000000100000035
raw: ffffea0007397720 ffffea0007331620 ffff8801dac001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cdb74180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801cdb74200: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801cdb74280: 02 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
                   ^
 ffff8801cdb74300: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801cdb74380: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
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