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BUG: KASAN: use-after-free in ocfs2_find_smallest_chain fs/ocfs2/suballoc.c:413 [inline]
BUG: KASAN: use-after-free in ocfs2_block_group_alloc_contig fs/ocfs2/suballoc.c:430 [inline]
BUG: KASAN: use-after-free in ocfs2_block_group_alloc fs/ocfs2/suballoc.c:699 [inline]
BUG: KASAN: use-after-free in ocfs2_reserve_suballoc_bits+0xdd0/0x4640 fs/ocfs2/suballoc.c:834
Read of size 4 at addr ffff888052ec6004 by task syz.0.0/5329

CPU: 0 UID: 0 PID: 5329 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 ocfs2_find_smallest_chain fs/ocfs2/suballoc.c:413 [inline]
 ocfs2_block_group_alloc_contig fs/ocfs2/suballoc.c:430 [inline]
 ocfs2_block_group_alloc fs/ocfs2/suballoc.c:699 [inline]
 ocfs2_reserve_suballoc_bits+0xdd0/0x4640 fs/ocfs2/suballoc.c:834
 ocfs2_reserve_new_metadata_blocks+0x403/0x940 fs/ocfs2/suballoc.c:984
 ocfs2_init_xattr_set_ctxt+0x307/0x700 fs/ocfs2/xattr.c:3277
 ocfs2_xattr_set+0xb70/0x11f0 fs/ocfs2/xattr.c:3634
 __vfs_setxattr+0x43c/0x480 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
 vfs_setxattr+0x16b/0x2f0 fs/xattr.c:321
 do_setxattr fs/xattr.c:636 [inline]
 filename_setxattr+0x274/0x600 fs/xattr.c:665
 path_setxattrat+0x364/0x3a0 fs/xattr.c:713
 __do_sys_setxattr fs/xattr.c:747 [inline]
 __se_sys_setxattr fs/xattr.c:743 [inline]
 __x64_sys_setxattr+0xbc/0xe0 fs/xattr.c:743
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f54db58f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f54dc340038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f54db7e6090 RCX: 00007f54db58f749
RDX: 0000200000000400 RSI: 00002000000003c0 RDI: 0000200000000380
RBP: 00007f54db613f91 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000055 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f54db7e6128 R14: 00007f54db7e6090 R15: 00007ffe78554818
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x52ec6
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 ffffea00014bb1c8 ffff88801fe403b0 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffff888052ec5f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888052ec5f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888052ec6000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888052ec6080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888052ec6100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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