syzbot

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BUG: KASAN: use-after-free in sysv_new_block+0x7d0/0xa90 fs/sysv/balloc.c:113
Read of size 4 at addr ffff88807c371ffc by task syz-executor145/8916

CPU: 0 PID: 8916 Comm: syz-executor145 Not tainted 6.4.0-rc7-syzkaller-00072-gdad9774deaf1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
 print_report mm/kasan/report.c:462 [inline]
 kasan_report+0x11c/0x130 mm/kasan/report.c:572
 sysv_new_block+0x7d0/0xa90 fs/sysv/balloc.c:113
 alloc_branch fs/sysv/itree.c:134 [inline]
 get_block+0x26b/0x1580 fs/sysv/itree.c:251
 __block_write_begin_int+0x3bd/0x14b0 fs/buffer.c:2064
 __block_write_begin fs/buffer.c:2114 [inline]
 block_write_begin+0xb9/0x4d0 fs/buffer.c:2175
 sysv_write_begin+0x31/0xd0 fs/sysv/itree.c:485
 generic_perform_write+0x256/0x570 mm/filemap.c:3929
 __generic_file_write_iter+0x2ae/0x500 mm/filemap.c:4057
 generic_file_write_iter+0xe3/0x350 mm/filemap.c:4089
 call_write_iter include/linux/fs.h:1868 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x945/0xd50 fs/read_write.c:584
 ksys_write+0x12b/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f89742b9e99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 17 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe60074b98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f89742b9e99
RDX: 00000000fffffd5e RSI: 000000002000ad00 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000140 R09: 0000000000000140
R10: 0000000000009e07 R11: 0000000000000246 R12: 00007ffe60074bd0
R13: 00007ffe60074bac R14: 431bde82d7b634db R15: 00007ffe60074bb0
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001f0dc40 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x7c371
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 ffffea0001f0d7c8 ffffea0001f0b7c8 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 4994, tgid 4994 (udevd), ts 71356591820, free_ts 203890536444
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1731
 prep_new_page mm/page_alloc.c:1738 [inline]
 get_page_from_freelist+0xf41/0x2c00 mm/page_alloc.c:3502
 __alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4768
 __folio_alloc+0x16/0x40 mm/page_alloc.c:4800
 vma_alloc_folio+0x155/0x890 mm/mempolicy.c:2240
 wp_page_copy mm/memory.c:3074 [inline]
 do_wp_page+0x81c/0x33c0 mm/memory.c:3432
 handle_pte_fault mm/memory.c:4964 [inline]
 __handle_mm_fault+0x1635/0x41c0 mm/memory.c:5089
 handle_mm_fault+0x2af/0x9f0 mm/memory.c:5243
 do_user_addr_fault+0x2ca/0x1210 arch/x86/mm/fault.c:1349
 handle_page_fault arch/x86/mm/fault.c:1534 [inline]
 exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
 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:1302 [inline]
 free_unref_page_prepare+0x62e/0xcb0 mm/page_alloc.c:2564
 free_unref_page_list+0xe3/0xa70 mm/page_alloc.c:2705
 release_pages+0xcd8/0x1380 mm/swap.c:1042
 tlb_batch_pages_flush+0xa8/0x1a0 mm/mmu_gather.c:97
 tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
 tlb_flush_mmu mm/mmu_gather.c:299 [inline]
 tlb_finish_mmu+0x14b/0x7e0 mm/mmu_gather.c:391
 exit_mmap+0x2b2/0x930 mm/mmap.c:3120
 __mmput+0x128/0x4c0 kernel/fork.c:1351
 mmput+0x60/0x70 kernel/fork.c:1373
 exit_mm kernel/exit.c:567 [inline]
 do_exit+0x9b0/0x29b0 kernel/exit.c:861
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1033
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88807c371e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807c371f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88807c371f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff88807c372000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807c372080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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