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BUG: KASAN: use-after-free in sysv_new_inode+0xfc7/0x1160 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff888071d2f1ce by task syz.4.19/6076

CPU: 1 UID: 0 PID: 6076 Comm: syz.4.19 Not tainted 6.13.0-rc1-syzkaller-00001-ge70140ba0d2b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 sysv_new_inode+0xfc7/0x1160 fs/sysv/ialloc.c:153
 sysv_mknod+0x4e/0xe0 fs/sysv/namei.c:53
 vfs_create+0x23c/0x3d0 fs/namei.c:3348
 do_mknodat+0x447/0x5b0 fs/namei.c:4239
 __do_sys_mknod fs/namei.c:4272 [inline]
 __se_sys_mknod fs/namei.c:4270 [inline]
 __x64_sys_mknod+0x8c/0xa0 fs/namei.c:4270
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdbc097ff19
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:00007ffd18796258 EFLAGS: 00000246 ORIG_RAX: 0000000000000085
RAX: ffffffffffffffda RBX: 00007fdbc0b45fa0 RCX: 00007fdbc097ff19
RDX: 0000000000000009 RSI: 0000000000000020 RDI: 0000000020000180
RBP: 00007fdbc09f3986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdbc0b45fa0 R14: 00007fdbc0b45fa0 R15: 0000000000000acf
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x756b6 pfn:0x71d2f
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 00000000000756b6 0000000000000000 00000000ffffffff 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 6078, tgid 6078 (syz.3.18), ts 376844688759, free_ts 407509240148
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1556
 prep_new_page mm/page_alloc.c:1564 [inline]
 get_page_from_freelist+0x3651/0x37a0 mm/page_alloc.c:3474
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4751
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 alloc_pages_noprof mm/mempolicy.c:2344 [inline]
 folio_alloc_noprof+0x128/0x180 mm/mempolicy.c:2351
 filemap_alloc_folio_noprof+0xdf/0x500 mm/filemap.c:1009
 do_read_cache_folio+0x2eb/0x850 mm/filemap.c:3788
 read_mapping_folio include/linux/pagemap.h:1011 [inline]
 dir_get_folio fs/sysv/dir.c:64 [inline]
 sysv_find_entry+0x16a/0x4b0 fs/sysv/dir.c:154
 sysv_inode_by_name+0x98/0x2a0 fs/sysv/dir.c:370
 sysv_lookup+0x6b/0xe0 fs/sysv/namei.c:38
 lookup_one_qstr_excl+0x11f/0x260 fs/namei.c:1692
 filename_create+0x297/0x540 fs/namei.c:4081
 do_mknodat+0x18b/0x5b0 fs/namei.c:4226
 __do_sys_mknod fs/namei.c:4272 [inline]
 __se_sys_mknod fs/namei.c:4270 [inline]
 __x64_sys_mknod+0x8c/0xa0 fs/namei.c:4270
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6078 tgid 6078 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_folios+0xf38/0x1a60 mm/page_alloc.c:2704
 folios_put_refs+0x76c/0x860 mm/swap.c:962
 folio_batch_release include/linux/pagevec.h:101 [inline]
 truncate_inode_pages_range+0x47b/0xfc0 mm/truncate.c:330
 sysv_evict_inode+0x2b/0x110 fs/sysv/inode.c:289
 evict+0x4e8/0x9a0 fs/inode.c:796
 __dentry_kill+0x20d/0x630 fs/dcache.c:625
 dput+0x19f/0x2b0 fs/dcache.c:867
 shrink_dcache_for_umount+0xb4/0x180 fs/dcache.c:1577
 generic_shutdown_super+0x6a/0x2d0 fs/super.c:620
 kill_block_super+0x44/0x90 fs/super.c:1710
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373
 task_work_run+0x24f/0x310 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa2f/0x28e0 kernel/exit.c:938
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 get_signal+0x16b2/0x1750 kernel/signal.c:3017

Memory state around the buggy address:
 ffff888071d2f080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888071d2f100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888071d2f180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff888071d2f200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888071d2f280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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