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BUG: KASAN: use-after-free in take_option security/selinux/hooks.c:2619 [inline]
BUG: KASAN: use-after-free in selinux_sb_copy_data+0x1cd/0x380 security/selinux/hooks.c:2674
Write of size 10 at addr ffff88019fa74000 by task syz-executor3/15856

CPU: 0 PID: 15856 Comm: syz-executor3 Not tainted 4.9.96-g320d53a #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801cd9574c8 ffffffff81eb0b69 ffffea00067e9d00 ffff88019fa74000
 0000000000000001 ffff88019fa74000 000000000000000a ffff8801cd957500
 ffffffff8156540b ffff88019fa74000 000000000000000a 0000000000000001
Call Trace:
 [<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8156540b>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81565815>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81565815>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff815382ff>] check_memory_region_inline mm/kasan/kasan.c:318 [inline]
 [<ffffffff815382ff>] check_memory_region+0x14f/0x1b0 mm/kasan/kasan.c:325
 [<ffffffff81538957>] memcpy+0x37/0x50 mm/kasan/kasan.c:361
 [<ffffffff81d0598d>] take_option security/selinux/hooks.c:2619 [inline]
 [<ffffffff81d0598d>] selinux_sb_copy_data+0x1cd/0x380 security/selinux/hooks.c:2674
 [<ffffffff81ce74fb>] security_sb_copy_data+0x7b/0xb0 security/security.c:283
 [<ffffffff81977c76>] parse_security_options+0x36/0x90 fs/btrfs/super.c:1493
 [<ffffffff81988ca3>] btrfs_mount+0x2f3/0x2bc0 fs/btrfs/super.c:1572
 [<ffffffff8157badc>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815db081>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815db3c0>] vfs_kern_mount+0x40/0x60 fs/namespace.c:973
 [<ffffffff81988dbb>] mount_subvol fs/btrfs/super.c:1395 [inline]
 [<ffffffff81988dbb>] btrfs_mount+0x40b/0x2bc0 fs/btrfs/super.c:1566
 [<ffffffff8157badc>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815db081>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e29a9>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e29a9>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e29a9>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e56fe>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e56fe>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f3313>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Allocated by task 2386:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:505
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:609
 kmem_cache_alloc_trace+0xfd/0x2b0 mm/slub.c:2742
 kmalloc include/linux/slab.h:490 [inline]
 kzalloc include/linux/slab.h:636 [inline]
 seq_open+0x83/0x200 fs/seq_file.c:67
 kernfs_fop_open+0x506/0xaf0 fs/kernfs/file.c:705
 do_dentry_open+0x703/0xc80 fs/open.c:766
 vfs_open+0x11c/0x210 fs/open.c:879
 do_last fs/namei.c:3410 [inline]
 path_openat+0x758/0x3590 fs/namei.c:3534
 do_filp_open+0x197/0x270 fs/namei.c:3568
 do_sys_open+0x30d/0x5c0 fs/open.c:1072
 SYSC_open fs/open.c:1090 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1085
 do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Freed by task 2386:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:505
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:582
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xfb/0x310 mm/slub.c:3878
 seq_release+0x59/0x70 fs/seq_file.c:372
 kernfs_fop_release+0xcb/0x140 fs/kernfs/file.c:742
 __fput+0x263/0x700 fs/file_table.c:208
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x10c/0x180 kernel/task_work.c:116
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the object at ffff88019fa74000
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes inside of
 256-byte region [ffff88019fa74000, ffff88019fa74100)
The buggy address belongs to the page:
page:ffffea00067e9d00 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000080(slab)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88019fa73f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88019fa73f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88019fa74000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88019fa74080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88019fa74100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
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