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BUG: KASAN: use-after-free in sysv_new_inode+0xfd3/0x1170 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff88807a16f1ce by task syz.1.1722/10344

CPU: 1 PID: 10344 Comm: syz.1.1722 Not tainted 6.10.0-rc6-syzkaller-00223-gc6653f49e4fd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 sysv_new_inode+0xfd3/0x1170 fs/sysv/ialloc.c:153
 sysv_mknod+0x4e/0xe0 fs/sysv/namei.c:53
 lookup_open fs/namei.c:3505 [inline]
 open_last_lookups fs/namei.c:3574 [inline]
 path_openat+0x1a86/0x35f0 fs/namei.c:3810
 do_filp_open+0x235/0x490 fs/namei.c:3840
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1413
 do_sys_open fs/open.c:1428 [inline]
 __do_sys_open fs/open.c:1436 [inline]
 __se_sys_open fs/open.c:1432 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1432
 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: 0033:0x7f2589775bd9
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:00007f258a50f048 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f2589903f60 RCX: 00007f2589775bd9
RDX: 0000000000000000 RSI: 0000000000060840 RDI: 00000000209e1000
RBP: 00007f25897e4aa1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f2589903f60 R15: 00007ffceeaf2c58
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xc7 pfn:0x7a16f
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00011f7fc8 ffffea0000467648 0000000000000000
raw: 00000000000000c7 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 0x100cca(GFP_HIGHUSER_MOVABLE), pid 21661, tgid 21660 (syz.0.5733), ts 1339007069813, free_ts 1340486708167
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1473
 prep_new_page mm/page_alloc.c:1481 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3425
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4683
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 shmem_alloc_folio mm/shmem.c:1628 [inline]
 shmem_alloc_and_add_folio+0x24d/0xdb0 mm/shmem.c:1668
 shmem_get_folio_gfp+0x82d/0x1f50 mm/shmem.c:2055
 shmem_get_folio mm/shmem.c:2160 [inline]
 shmem_write_begin+0x170/0x4d0 mm/shmem.c:2743
 generic_perform_write+0x324/0x640 mm/filemap.c:4015
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2919
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa74/0xc90 fs/read_write.c:590
 ksys_write+0x1a0/0x2c0 fs/read_write.c:643
 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 21661 tgid 21660 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1093 [inline]
 free_unref_folios+0xf23/0x19e0 mm/page_alloc.c:2637
 folios_put_refs+0x93a/0xa60 mm/swap.c:1024
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x6de/0x1df0 mm/shmem.c:1005
 shmem_truncate_range mm/shmem.c:1114 [inline]
 shmem_evict_inode+0x29b/0xa60 mm/shmem.c:1242
 evict+0x2aa/0x630 fs/inode.c:667
 __dentry_kill+0x20d/0x630 fs/dcache.c:603
 dput+0x19f/0x2b0 fs/dcache.c:845
 __fput+0x5f8/0x8a0 fs/file_table.c:430
 __do_sys_close fs/open.c:1563 [inline]
 __se_sys_close fs/open.c:1548 [inline]
 __x64_sys_close+0x7f/0x110 fs/open.c:1548
 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

Memory state around the buggy address:
 ffff88807a16f080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807a16f100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807a16f180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                              ^
 ffff88807a16f200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807a16f280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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