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BUG: KASAN: use-after-free in sysv_new_inode+0xed4/0x1190 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff888049fc01ce by task syz-executor.2/6647

CPU: 3 PID: 6647 Comm: syz-executor.2 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 sysv_new_inode+0xed4/0x1190 fs/sysv/ialloc.c:153
 sysv_mknod fs/sysv/namei.c:53 [inline]
 sysv_create+0x20/0xf0 fs/sysv/namei.c:67
 lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3505
 open_last_lookups fs/namei.c:3574 [inline]
 path_openat+0x92f/0x29f0 fs/namei.c:3804
 do_filp_open+0x1dc/0x430 fs/namei.c:3834
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1405
 do_sys_open fs/open.c:1420 [inline]
 __do_sys_openat fs/open.c:1436 [inline]
 __se_sys_openat fs/open.c:1431 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1431
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f496287cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f496359a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f49629abf80 RCX: 00007f496287cee9
RDX: 000000000000275a RSI: 0000000020000080 RDI: ffffffffffffff9c
RBP: 00007f49628c949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f49629abf80 R15: 00007ffcee4ffee8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x6d544 pfn:0x49fc0
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffff7f(buddy)
raw: 00fff00000000000 ffffea0000f50308 ffffea00015cc308 0000000000000000
raw: 000000000006d544 0000000000000002 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 6475, tgid 6474 (syz-executor.1), ts 255074583046, free_ts 275954877893
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1468
 prep_new_page mm/page_alloc.c:1476 [inline]
 get_page_from_freelist+0x136a/0x2e50 mm/page_alloc.c:3420
 __alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4678
 alloc_pages_mpol_noprof+0x275/0x610 mm/mempolicy.c:2265
 folio_alloc_noprof+0x1e/0xc0 mm/mempolicy.c:2343
 filemap_alloc_folio_noprof+0x3ba/0x490 mm/filemap.c:1008
 do_read_cache_folio+0x1b6/0x540 mm/filemap.c:3752
 do_read_cache_page mm/filemap.c:3854 [inline]
 read_cache_page+0x5b/0x160 mm/filemap.c:3863
 read_mapping_page include/linux/pagemap.h:896 [inline]
 dir_get_page fs/sysv/dir.c:64 [inline]
 sysv_find_entry+0x1e5/0x690 fs/sysv/dir.c:157
 sysv_inode_by_name+0x71/0x3b0 fs/sysv/dir.c:374
 sysv_lookup fs/sysv/namei.c:38 [inline]
 sysv_lookup+0x8c/0x100 fs/sysv/namei.c:31
 lookup_open.isra.0+0x928/0x13c0 fs/namei.c:3483
 open_last_lookups fs/namei.c:3574 [inline]
 path_openat+0x92f/0x29f0 fs/namei.c:3804
 do_filp_open+0x1dc/0x430 fs/namei.c:3834
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1405
 do_sys_open fs/open.c:1420 [inline]
 __do_sys_openat fs/open.c:1436 [inline]
 __se_sys_openat fs/open.c:1431 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1431
page last free pid 6475 tgid 6474 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1088 [inline]
 free_unref_folios+0x991/0x1310 mm/page_alloc.c:2632
 folios_put_refs+0x487/0x6d0 mm/swap.c:1024
 folio_batch_release include/linux/pagevec.h:101 [inline]
 truncate_inode_pages_range+0x334/0xe80 mm/truncate.c:362
 sysv_evict_inode+0x20/0x110 fs/sysv/inode.c:289
 evict+0x2ed/0x6c0 fs/inode.c:667
 iput_final fs/inode.c:1741 [inline]
 iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
 iput+0x5c/0x80 fs/inode.c:1757
 dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
 __dentry_kill+0x1d0/0x600 fs/dcache.c:603
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:845
 dput fs/dcache.c:835 [inline]
 do_one_tree fs/dcache.c:1541 [inline]
 shrink_dcache_for_umount+0x131/0x390 fs/dcache.c:1555
 generic_shutdown_super+0x76/0x3d0 fs/super.c:620
 kill_block_super+0x3b/0x90 fs/super.c:1676
 deactivate_locked_super+0xbe/0x1a0 fs/super.c:473
 deactivate_super+0xde/0x100 fs/super.c:506
 cleanup_mnt+0x222/0x450 fs/namespace.c:1267

Memory state around the buggy address:
 ffff888049fc0080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888049fc0100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888049fc0180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff888049fc0200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888049fc0280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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