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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 ffff88805c73d1ce by task syz-executor.2/8719

CPU: 0 PID: 8719 Comm: syz-executor.2 Not tainted 6.9.0-rc6-syzkaller-00005-gb947cc5bf6d7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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
 vfs_create+0x23c/0x390 fs/namei.c:3199
 do_mknodat+0x447/0x5b0 fs/namei.c:4051
 __do_sys_mknod fs/namei.c:4084 [inline]
 __se_sys_mknod fs/namei.c:4082 [inline]
 __x64_sys_mknod+0x8e/0xa0 fs/namei.c:4082
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc86627dea9
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:00007fc866f170c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000085
RAX: ffffffffffffffda RBX: 00007fc8663abf80 RCX: 00007fc86627dea9
RDX: 0000000000000704 RSI: 0000000000000000 RDI: 0000000020000080
RBP: 00007fc8662ca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fc8663abf80 R15: 00007ffce73816b8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x5c73d
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 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 10566, tgid -1594203839 (syz-executor.3), ts 10567, free_ts 399363093550
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
 prep_new_page mm/page_alloc.c:1541 [inline]
 get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
 __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
 alloc_pages_mpol+0x3e8/0x680 mm/mempolicy.c:2264
 shmem_alloc_folio mm/shmem.c:1628 [inline]
 shmem_alloc_and_add_folio+0x24d/0xbc0 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:2744
 generic_perform_write+0x322/0x640 mm/filemap.c:3974
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2920
 call_write_iter include/linux/fs.h:2110 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa84/0xcb0 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+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 10364 tgid 10364 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1141 [inline]
 free_unref_page_prepare+0x97b/0xaa0 mm/page_alloc.c:2347
 free_unref_folios+0x1f2/0xc10 mm/page_alloc.c:2536
 folios_put_refs+0x93a/0xa60 mm/swap.c:1034
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x6d9/0x1df0 mm/shmem.c:1005
 shmem_truncate_range mm/shmem.c:1114 [inline]
 shmem_evict_inode+0x29b/0xa60 mm/shmem.c:1242
 evict+0x2a8/0x630 fs/inode.c:667
 __dentry_kill+0x20d/0x630 fs/dcache.c:603
 dput+0x19f/0x2b0 fs/dcache.c:845
 __fput+0x678/0x8a0 fs/file_table.c:430
 task_work_run+0x24f/0x310 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218
 do_syscall_64+0x102/0x240 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88805c73d080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805c73d100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88805c73d180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff88805c73d200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805c73d280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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