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BUG: KASAN: use-after-free in ext4_xattr_set_entry+0x2e28/0x2f00 fs/ext4/xattr.c:1602
Read of size 4 at addr ffff8881af902004 by task syz-executor.1/11419

CPU: 0 PID: 11419 Comm: syz-executor.1 Not tainted 4.14.150+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 ext4_xattr_set_entry+0x2e28/0x2f00 fs/ext4/xattr.c:1602
 ext4_xattr_ibody_set+0x73/0x280 fs/ext4/xattr.c:2238
 ext4_xattr_set_handle+0x508/0xdd0 fs/ext4/xattr.c:2394
 ext4_initxattrs+0xb5/0x110 fs/ext4/xattr_security.c:43
 security_inode_init_security security/security.c:493 [inline]
 security_inode_init_security+0x246/0x330 security/security.c:466
 __ext4_new_inode+0x336f/0x4850 fs/ext4/ialloc.c:1166
 ext4_mkdir+0x2f7/0xb50 fs/ext4/namei.c:2776
 vfs_mkdir2+0x3c7/0x640 fs/namei.c:3967
 SYSC_mkdirat fs/namei.c:3996 [inline]
 SyS_mkdirat+0x125/0x220 fs/namei.c:3980
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459367
RSP: 002b:00007fff581d2298 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 000000000003a2f8 RCX: 0000000000459367
RDX: 0000000000000008 RSI: 00000000000001c0 RDI: 00007fff581d2470
RBP: 0000000000000001 R08: 000000000000f8c0 R09: 0000000000008940
R10: 0000000000000011 R11: 0000000000000246 R12: 00000000000000c2
R13: 00007fff581d2470 R14: 8421084210842109 R15: 00007fff581d247c

The buggy address belongs to the page:
page:ffffea0006be4080 count:0 mapcount:-127 mapping:          (null) index:0x1
flags: 0x4000000000000000()
raw: 4000000000000000 0000000000000000 0000000000000001 00000000ffffff80
raw: ffffea0006be42a0 ffffea0006be2d20 0000000000000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881af901f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881af901f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881af902000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8881af902080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881af902100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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