Re: [syzbot] [mm?] BUG: corrupted list in __folio_undo_large_rmappable

[Hugh Dickins]

On Wed, 10 Jul 2024, syzbot wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    82d01fe6ee52 Add linux-next specific files for 20240709
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=14904441980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=95a20e7acf357998
> dashboard link: https://syzkaller.appspot.com/bug?extid=a2cc273ad0e5a4c15302
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15882a49980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172aba49980000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/12dcacb06142/disk-82d01fe6.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/6ef954821378/vmlinux-82d01fe6.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9ebf01d42887/bzImage-82d01fe6.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a2cc273ad0e5a4c15302@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> list_del corruption, ffffea0001eb8090->next is NULL
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:53!
> Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
> CPU: 0 UID: 0 PID: 5105 Comm: syz-executor331 Not tainted 6.10.0-rc7-next-20240709-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
> RIP: 0010:__list_del_entry_valid_or_report+0xd0/0x140 lib/list_debug.c:52
> Code: 06 e2 42 fd 48 8b 13 4c 39 fa 75 6b b0 01 5b 41 5c 41 5e 41 5f c3 cc cc cc cc 48 c7 c7 a0 9b 20 8c 4c 89 fe e8 71 e0 d7 06 90 <0f> 0b 48 c7 c7 00 9c 20 8c 4c 89 fe e8 5f e0 d7 06 90 0f 0b 48 c7
> RSP: 0018:ffffc900034df410 EFLAGS: 00010046
> RAX: 0000000000000033 RBX: ffff888140e81000 RCX: f885dda17ff31200
> RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
> RBP: ffffea0001eb8090 R08: ffffffff8173a779 R09: 1ffff9200069be1c
> R10: dffffc0000000000 R11: fffff5200069be1d R12: dffffc0000000000
> R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0001eb8090
> FS:  00007fe27183f6c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000200d1a00 CR3: 0000000021fbe000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __list_del_entry_valid include/linux/list.h:124 [inline]
>  __list_del_entry include/linux/list.h:215 [inline]
>  list_del_init include/linux/list.h:287 [inline]
>  __folio_undo_large_rmappable+0x104/0x230 mm/huge_memory.c:3289
>  __folio_migrate_mapping+0x6c1/0x3490 mm/migrate.c:418
>  __migrate_folio mm/migrate.c:693 [inline]
>  migrate_folio+0x111/0x260 mm/migrate.c:720
>  move_to_new_folio+0x306/0x12e0
>  unmap_and_move_huge_page mm/migrate.c:1444 [inline]
>  migrate_hugetlbs mm/migrate.c:1563 [inline]
>  migrate_pages+0xb74/0x3460 mm/migrate.c:1960
>  do_mbind mm/mempolicy.c:1388 [inline]
>  kernel_mbind mm/mempolicy.c:1531 [inline]
>  __do_sys_mbind mm/mempolicy.c:1605 [inline]
>  __se_sys_mbind+0x1490/0x19f0 mm/mempolicy.c:1601
>  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: 0033:0x7fe2718a4d39
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 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 b0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fe27183f208 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
> RAX: ffffffffffffffda RBX: 00007fe27192f338 RCX: 00007fe2718a4d39
> RDX: 0000000000000000 RSI: 0000000000004000 RDI: 0000000020199000
> RBP: 00007fe27192f330 R08: 0000000000000000 R09: 0000000000000003
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe2718fc604
> R13: 00007fe2718fc008 R14: 7277682f7665642f R15: 00000000ffffff1f
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__list_del_entry_valid_or_report+0xd0/0x140 lib/list_debug.c:52
> Code: 06 e2 42 fd 48 8b 13 4c 39 fa 75 6b b0 01 5b 41 5c 41 5e 41 5f c3 cc cc cc cc 48 c7 c7 a0 9b 20 8c 4c 89 fe e8 71 e0 d7 06 90 <0f> 0b 48 c7 c7 00 9c 20 8c 4c 89 fe e8 5f e0 d7 06 90 0f 0b 48 c7
> RSP: 0018:ffffc900034df410 EFLAGS: 00010046
> RAX: 0000000000000033 RBX: ffff888140e81000 RCX: f885dda17ff31200
> RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
> RBP: ffffea0001eb8090 R08: ffffffff8173a779 R09: 1ffff9200069be1c
> R10: dffffc0000000000 R11: fffff5200069be1d R12: dffffc0000000000
> R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0001eb8090
> FS:  00007fe27183f6c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000200d1a00 CR3: 0000000021fbe000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> 
> ---
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> 
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> 
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> 
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#syz fix: mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio