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BUG: KASAN: use-after-free in ext4_xattr_set_entry+0x35c1/0x3750 fs/ext4/xattr.c:1600
Read of size 4 at addr ffff888063dfe064 by task syz-executor.2/17736

CPU: 1 PID: 17736 Comm: syz-executor.2 Not tainted 5.1.0-rc6-next-20190426 #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:316
 kasan_report+0x12/0x20 mm/kasan/common.c:620
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
 ext4_xattr_set_entry+0x35c1/0x3750 fs/ext4/xattr.c:1600
 ext4_xattr_ibody_set+0x80/0x2b0 fs/ext4/xattr.c:2236
 ext4_xattr_set_handle+0x5d2/0x1010 fs/ext4/xattr.c:2392
 __ext4_set_acl+0x358/0x5a0 fs/ext4/acl.c:214
 ext4_set_acl+0x2c5/0x4f0 fs/ext4/acl.c:255
 set_posix_acl fs/posix_acl.c:874 [inline]
 set_posix_acl+0x233/0x2f0 fs/posix_acl.c:857
 posix_acl_xattr_set+0x96/0x140 fs/posix_acl.c:892
 __vfs_setxattr+0x121/0x190 fs/xattr.c:149
 __vfs_setxattr_noperm+0x11c/0x410 fs/xattr.c:180
 vfs_setxattr+0xda/0x100 fs/xattr.c:223
 setxattr+0x26f/0x380 fs/xattr.c:450
 path_setxattr+0x197/0x1b0 fs/xattr.c:469
 __do_sys_setxattr fs/xattr.c:484 [inline]
 __se_sys_setxattr fs/xattr.c:480 [inline]
 __x64_sys_setxattr+0xc4/0x150 fs/xattr.c:480
 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458da9
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3c65837c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458da9
RDX: 0000000020000b00 RSI: 0000000020000080 RDI: 0000000020000000
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000003c R11: 0000000000000246 R12: 00007f3c658386d4
R13: 00000000004bf5f8 R14: 00000000004dcda0 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea00018f7f80 count:0 mapcount:-128 mapping:0000000000000000 index:0x1
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 ffffea00020b3288 ffffea0001dab188 0000000000000000
raw: 0000000000000001 0000000000000001 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888063dfdf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888063dfdf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888063dfe000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                       ^
 ffff888063dfe080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888063dfe100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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