syzbot

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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 ffff8880782af1ce by task syz-executor188/5865

CPU: 1 UID: 0 PID: 5865 Comm: syz-executor188 Not tainted 6.12.0-syzkaller-01782-gbf9aa14fc523 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
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:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 sysv_new_inode+0xfc7/0x1160 fs/sysv/ialloc.c:153
 sysv_mknod+0x4e/0xe0 fs/sysv/namei.c:53
 lookup_open fs/namei.c:3649 [inline]
 open_last_lookups fs/namei.c:3748 [inline]
 path_openat+0x1c03/0x3590 fs/namei.c:3984
 do_filp_open+0x27f/0x4e0 fs/namei.c:4014
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1398
 do_sys_open fs/open.c:1413 [inline]
 __do_sys_open fs/open.c:1421 [inline]
 __se_sys_open fs/open.c:1417 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1417
 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: 0033:0x7f282781d1d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffedfc42d28 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f282781d1d9
RDX: 0000000000000000 RSI: 00100000001a1540 RDI: 0000000020000580
RBP: 00000000ffffffff R08: 0000000000009e7f R09: 0000000000000000
R10: 00007ffedfc42db0 R11: 0000000000000246 R12: 00007ffedfc42d70
R13: 00007ffedfc42db0 R14: 0000000000010000 R15: 0000000000000003
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7f8af3c7b pfn:0x782af
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 00000007f8af3c7b 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 5825, tgid 5825 (sshd), ts 55873467811, free_ts 55931325869
 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+0x363e/0x3790 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
 folio_alloc_mpol_noprof mm/mempolicy.c:2283 [inline]
 vma_alloc_folio_noprof+0x12e/0x230 mm/mempolicy.c:2314
 folio_prealloc+0x31/0x170
 alloc_anon_folio mm/memory.c:4727 [inline]
 do_anonymous_page mm/memory.c:4784 [inline]
 do_pte_missing mm/memory.c:3963 [inline]
 handle_pte_fault+0x24dd/0x6820 mm/memory.c:5766
 __handle_mm_fault mm/memory.c:5909 [inline]
 handle_mm_fault+0x1053/0x1ad0 mm/memory.c:6077
 do_user_addr_fault arch/x86/mm/fault.c:1338 [inline]
 handle_page_fault arch/x86/mm/fault.c:1481 [inline]
 exc_page_fault+0x459/0x8c0 arch/x86/mm/fault.c:1539
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 5825 tgid 5825 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_folios+0xf21/0x1a10 mm/page_alloc.c:2704
 folios_put_refs+0x76c/0x860 mm/swap.c:993
 free_pages_and_swap_cache+0x2ea/0x690 mm/swap_state.c:332
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:366 [inline]
 tlb_flush_mmu+0x3a3/0x680 mm/mmu_gather.c:373
 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:465
 vms_clear_ptes+0x437/0x530 mm/vma.c:1102
 vms_complete_munmap_vmas+0x214/0x8f0 mm/vma.c:1144
 do_vmi_align_munmap+0x5ef/0x6f0 mm/vma.c:1353
 do_vmi_munmap+0x24e/0x2d0 mm/vma.c:1401
 __vm_munmap+0x24c/0x480 mm/mmap.c:1623
 __do_sys_munmap mm/mmap.c:1640 [inline]
 __se_sys_munmap mm/mmap.c:1637 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1637
 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:
 ffff8880782af080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880782af100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880782af180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8880782af200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880782af280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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