Re: [syzbot] [mm?] general protection fault in __pte_offset_map_lock (2)

[David Hildenbrand <david@redhat.com>]

On 06.08.25 09:43, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    5998f2bca43e Merge tag 'exfat-for-6.17-rc1' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=136cc434580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=eb90b5976661bfd8
> dashboard link: https://syzkaller.appspot.com/bug?extid=45ad2baf16fce6bc81f3
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=102eb6a2580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=134d16a2580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/616a65da77ea/disk-5998f2bc.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/0f3838a6bd07/vmlinux-5998f2bc.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/298a57ed56ee/bzImage-5998f2bc.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+45ad2baf16fce6bc81f3@syzkaller.appspotmail.com
> 
> Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
> CPU: 0 UID: 0 PID: 6221 Comm: syz.2.42 Not tainted 6.16.0-syzkaller-11741-g5998f2bca43e #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> RIP: 0010:kasan_byte_accessible+0x15/0x30 mm/kasan/generic.c:199
> Code: 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 48 b8 00 00 00 00 00 fc ff df 48 c1 ef 03 48 01 c7 <0f> b6 07 3c 07 0f 96 c0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
> RSP: 0018:ffffc90003cdf6d8 EFLAGS: 00010286
> RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff8b92232e RDI: dffffc0000000003
> RBP: 0000000000000018 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8b92232e
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff8881246ce000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f3e8b1dff98 CR3: 000000000e380000 CR4: 00000000003526f0
> Call Trace:
>   <TASK>
>   __kasan_check_byte+0x13/0x50 mm/kasan/common.c:567
>   kasan_check_byte include/linux/kasan.h:399 [inline]
>   lock_acquire kernel/locking/lockdep.c:5842 [inline]
>   lock_acquire+0xfc/0x350 kernel/locking/lockdep.c:5825
>   __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
>   _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
>   spin_lock include/linux/spinlock.h:351 [inline]
>   __pte_offset_map_lock+0x10f/0x310 mm/pgtable-generic.c:401
>   pte_offset_map_lock include/linux/mm.h:3029 [inline]
>   zap_pte_range mm/memory.c:1712 [inline]
>   zap_pmd_range mm/memory.c:1818 [inline]
>   zap_pud_range mm/memory.c:1847 [inline]
>   zap_p4d_range mm/memory.c:1868 [inline]
>   unmap_page_range+0xacf/0x42c0 mm/memory.c:1889
>   unmap_single_vma.constprop.0+0x153/0x240 mm/memory.c:1932
>   unmap_vmas+0x218/0x470 mm/memory.c:1976
>   exit_mmap+0x1b9/0xb90 mm/mmap.c:1280
>   __mmput+0x12a/0x410 kernel/fork.c:1129
>   mmput+0x62/0x70 kernel/fork.c:1152
>   exit_mm kernel/exit.c:582 [inline]
>   do_exit+0x7c7/0x2bf0 kernel/exit.c:949
>   do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
>   __do_sys_exit_group kernel/exit.c:1113 [inline]
>   __se_sys_exit_group kernel/exit.c:1111 [inline]
>   __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1111
>   x64_sys_call+0x14fa/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
>   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>   do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
>   entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f412178eb69
> Code: Unable to access opcode bytes at 0x7f412178eb3f.
> RSP: 002b:00007ffcf2965e78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f412178eb69
> RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 00007ffcf2965edc R08: 0000000af2965f6f R09: 00000000000927c0
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
> R13: 00000000000927c0 R14: 00000000000215e0 R15: 00007ffcf2965f30
>   </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:kasan_byte_accessible+0x15/0x30 mm/kasan/generic.c:199
> Code: 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 48 b8 00 00 00 00 00 fc ff df 48 c1 ef 03 48 01 c7 <0f> b6 07 3c 07 0f 96 c0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
> RSP: 0018:ffffc90003cdf6d8 EFLAGS: 00010286
> RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff8b92232e RDI: dffffc0000000003
> RBP: 0000000000000018 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff8b92232e
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff8881246ce000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f3e8b1dff98 CR3: 000000000e380000 CR4: 00000000003526f0
> ----------------
> Code disassembly (best guess):
>     0:	00 00                	add    %al,(%rax)
>     2:	0f 1f 00             	nopl   (%rax)
>     5:	90                   	nop
>     6:	90                   	nop
>     7:	90                   	nop
>     8:	90                   	nop
>     9:	90                   	nop
>     a:	90                   	nop
>     b:	90                   	nop
>     c:	90                   	nop
>     d:	90                   	nop
>     e:	90                   	nop
>     f:	90                   	nop
>    10:	90                   	nop
>    11:	90                   	nop
>    12:	90                   	nop
>    13:	90                   	nop
>    14:	90                   	nop
>    15:	66 0f 1f 00          	nopw   (%rax)
>    19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
>    20:	fc ff df
>    23:	48 c1 ef 03          	shr    $0x3,%rdi
>    27:	48 01 c7             	add    %rax,%rdi
> * 2a:	0f b6 07             	movzbl (%rdi),%eax <-- trapping instruction
>    2d:	3c 07                	cmp    $0x7,%al
>    2f:	0f 96 c0             	setbe  %al
>    32:	c3                   	ret
>    33:	cc                   	int3
>    34:	cc                   	int3
>    35:	cc                   	int3
>    36:	cc                   	int3
>    37:	66                   	data16
>    38:	66                   	data16
>    39:	2e                   	cs
>    3a:	0f                   	.byte 0xf
>    3b:	1f                   	(bad)
>    3c:	84 00                	test   %al,(%rax)
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
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> If the report is already addressed, let syzbot know by replying with:
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> 
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> 
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> 
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> 

I assume this is fixed by [1]

[1] https://lkml.kernel.org/r/20250805035447.7958-1-21cnbao@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git 366a4532d96fc357998465133db34d34edb79e4c

-- 
Cheers,

David / dhildenb