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BUG: KASAN: use-after-free in mon_bin_vma_fault+0x378/0x400 drivers/usb/mon/mon_bin.c:1238
Read of size 8 at addr ffff8801bff22d90 by task syz-executor0/9618

CPU: 0 PID: 9618 Comm: syz-executor0 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_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 mon_bin_vma_fault+0x378/0x400 drivers/usb/mon/mon_bin.c:1238
 __do_fault+0xeb/0x30f mm/memory.c:3206
 do_read_fault mm/memory.c:3616 [inline]
 do_fault mm/memory.c:3716 [inline]
 handle_pte_fault mm/memory.c:3947 [inline]
 __handle_mm_fault+0x1d8f/0x3ce0 mm/memory.c:4071
 handle_mm_fault+0x38f/0x930 mm/memory.c:4108
 faultin_page mm/gup.c:502 [inline]
 __get_user_pages+0x50c/0x15f0 mm/gup.c:699
 populate_vma_page_range+0x20e/0x2f0 mm/gup.c:1200
 __mm_populate+0x23a/0x450 mm/gup.c:1250
 mm_populate include/linux/mm.h:2233 [inline]
 vm_mmap_pgoff+0x241/0x280 mm/util.c:338
 SYSC_mmap_pgoff mm/mmap.c:1544 [inline]
 SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1502
 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452ac9
RSP: 002b:00007f21f9a4ec58 EFLAGS: 00000212 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 0000000001000004 RSI: 0000000000004000 RDI: 0000000020ac6000
RBP: 0000000000000232 R08: 0000000000000015 R09: 0000000000000000
R10: 0000000000008011 R11: 0000000000000212 R12: 00000000006f0550
R13: 00000000ffffffff R14: 00007f21f9a4f6d4 R15: 0000000000000000

Allocated by task 9618:
 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
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3611
 kmalloc include/linux/slab.h:516 [inline]
 kzalloc include/linux/slab.h:705 [inline]
 mon_bin_open+0x1ae/0x4a0 drivers/usb/mon/mon_bin.c:703
 chrdev_open+0x257/0x730 fs/char_dev.c:417
 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+0x1f/0x96

Freed by task 9624:
 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
 mon_bin_ioctl+0x68d/0xd40 drivers/usb/mon/mon_bin.c:1040
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96

The buggy address belongs to the object at ffff8801bff22d80
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 16 bytes inside of
 2048-byte region [ffff8801bff22d80, ffff8801bff23580)
The buggy address belongs to the page:
page:00000000135a33ab count:1 mapcount:0 mapping:00000000678d68b2 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801bff22500 0000000000000000 0000000100000003
raw: ffffea0006a68f20 ffffea0006ff50a0 ffff8801dac00c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bff22c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801bff22d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801bff22d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8801bff22e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801bff22e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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