sysv_free_block: flc_count > flc_size
sysv_free_block: flc_count > flc_size
sysv_free_block: flc_count > flc_size
==================================================================
BUG: KASAN: use-after-free in sysv_new_block+0x7b7/0xa60 fs/sysv/balloc.c:113
Read of size 4 at addr ffff88806d4630c8 by task syz-executor.0/5721

CPU: 1 PID: 5721 Comm: syz-executor.0 Not tainted 6.7.0-rc1-syzkaller-00139-g6bc40e44f1dd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xc4/0x620 mm/kasan/report.c:475
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 sysv_new_block+0x7b7/0xa60 fs/sysv/balloc.c:113
 alloc_branch fs/sysv/itree.c:134 [inline]
 get_block+0x279/0x15c0 fs/sysv/itree.c:255
 __block_write_begin_int+0x3c0/0x1560 fs/buffer.c:2119
 __block_write_begin fs/buffer.c:2168 [inline]
 block_write_begin+0xb1/0x490 fs/buffer.c:2227
 sysv_write_begin+0x31/0xd0 fs/sysv/itree.c:490
 generic_perform_write+0x278/0x600 mm/filemap.c:3918
 __generic_file_write_iter+0x1f9/0x240 mm/filemap.c:4013
 generic_file_write_iter+0xe3/0x350 mm/filemap.c:4039
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x64f/0xdf0 fs/read_write.c:584
 ksys_write+0x12f/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fa35407c859
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:00007fa354d5a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa35419bf80 RCX: 00007fa35407c859
RDX: 00000000fffffe45 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 00007fa3540d8ad0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fa35419bf80 R15: 00007ffe142c6cf8
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001b518c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x6d463
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 ffffea0001b51908 ffffea0001b51888 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5518, tgid 5518 (sed), ts 78407120465, free_ts 78418348929
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2d0/0x350 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1544 [inline]
 get_page_from_freelist+0xa25/0x36d0 mm/page_alloc.c:3312
 __alloc_pages+0x22e/0x2420 mm/page_alloc.c:4568
 alloc_pages_mpol+0x258/0x5f0 mm/mempolicy.c:2133
 vma_alloc_folio+0xad/0x220 mm/mempolicy.c:2172
 wp_page_copy mm/memory.c:3119 [inline]
 do_wp_page+0xd8d/0x36b0 mm/memory.c:3510
 handle_pte_fault mm/memory.c:5054 [inline]
 __handle_mm_fault+0x1d7d/0x3d70 mm/memory.c:5179
 handle_mm_fault+0x47a/0xa10 mm/memory.c:5344
 do_user_addr_fault+0x30b/0x1000 arch/x86/mm/fault.c:1364
 handle_page_fault arch/x86/mm/fault.c:1505 [inline]
 exc_page_fault+0x5d/0xc0 arch/x86/mm/fault.c:1561
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1137 [inline]
 free_unref_page_prepare+0x4fa/0xaa0 mm/page_alloc.c:2347
 free_unref_page_list+0xe6/0xb40 mm/page_alloc.c:2533
 release_pages+0x32a/0x14f0 mm/swap.c:1042
 tlb_batch_pages_flush+0x9a/0x190 mm/mmu_gather.c:98
 tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
 tlb_flush_mmu mm/mmu_gather.c:300 [inline]
 tlb_finish_mmu+0x14b/0x6f0 mm/mmu_gather.c:392
 exit_mmap+0x38b/0xa70 mm/mmap.c:3321
 __mmput+0x12a/0x4d0 kernel/fork.c:1349
 mmput+0x62/0x70 kernel/fork.c:1371
 exit_mm kernel/exit.c:567 [inline]
 do_exit+0x9ad/0x2ae0 kernel/exit.c:858
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Memory state around the buggy address:
 ffff88806d462f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806d463000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806d463080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff88806d463100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806d463180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================