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Date: Wed, 3 Jan 2024 16:59:07 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: syzbot <syzbot+f8a023e0c6beabe2371a@syzkaller.appspotmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com,
 mhiramat@kernel.org, syzkaller-bugs@googlegroups.com, Linus Torvalds
 <torvalds@linux-foundation.org>
Subject: Re: [syzbot] [fs?] [trace?] BUG: unable to handle kernel paging
 request in tracefs_apply_options
Message-ID: <20240103165907.19d3a36c@gandalf.local.home>
In-Reply-To: <0000000000006bf22a060e117a8d@google.com>
References: <0000000000006bf22a060e117a8d@google.com>
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On Wed, 03 Jan 2024 13:41:31 -0800
syzbot <syzbot+f8a023e0c6beabe2371a@syzkaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    453f5db0619e Merge tag 'trace-v6.7-rc7' of git://git.kerne..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=10ec3829e80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f8e72bae38c079e4
> dashboard link: https://syzkaller.appspot.com/bug?extid=f8a023e0c6beabe2371a
> 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=1414af31e80000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15e52409e80000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/38b92a7149e8/disk-453f5db0.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/4f872267133f/vmlinux-453f5db0.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/587572061791/bzImage-453f5db0.xz
> 
> The issue was bisected to:
> 
> commit 7e8358edf503e87236c8d07f69ef0ed846dd5112
> Author: Steven Rostedt (Google) <rostedt@goodmis.org>
> Date:   Fri Dec 22 00:07:57 2023 +0000
> 
>     eventfs: Fix file and directory uid and gid ownership
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=108cd519e80000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=128cd519e80000
> console output: https://syzkaller.appspot.com/x/log.txt?x=148cd519e80000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f8a023e0c6beabe2371a@syzkaller.appspotmail.com
> Fixes: 7e8358edf503 ("eventfs: Fix file and directory uid and gid ownership")
> 
> BUG: unable to handle page fault for address: fffffffffffffff0
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD d734067 P4D d734067 PUD d736067 PMD 0 
> Oops: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 5056 Comm: syz-executor170 Not tainted 6.7.0-rc7-syzkaller-00049-g453f5db0619e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
> RIP: 0010:set_gid fs/tracefs/inode.c:224 [inline]
> RIP: 0010:tracefs_apply_options+0x4d0/0xa40 fs/tracefs/inode.c:337
> Code: 24 10 49 8b 1e 48 83 c3 f0 74 3d 48 89 d8 48 c1 e8 03 48 bd 00 00 00 00 00 fc ff df 80 3c 28 00 74 08 48 89 df e8 70 ff 88 fe <48> 8b 1b 48 89 de 48 83 e6 02 31 ff e8 bf fe 2c fe 48 83 e3 02 75
> RSP: 0018:ffffc900040ffca8 EFLAGS: 00010246
> RAX: 1ffffffffffffffe RBX: fffffffffffffff0 RCX: ffff888014bf5940
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffc900040ffc20
> RBP: dffffc0000000000 R08: 0000000000000003 R09: fffff5200081ff84
> R10: dffffc0000000000 R11: fffff5200081ff84 R12: ffff88801d743888
> R13: ffff88801b0c3710 R14: ffff88801d7437e8 R15: ffff88801d743810
> FS:  00005555557dd480(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: fffffffffffffff0 CR3: 000000001ec48000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  tracefs_remount+0x78/0x80 fs/tracefs/inode.c:353
>  reconfigure_super+0x440/0x870 fs/super.c:1143
>  do_remount fs/namespace.c:2884 [inline]

This is the same bug that was fixed by:

   https://lore.kernel.org/linux-trace-kernel/20240102151249.05da244d@gandalf.local.home/

And just waiting to be applied:

   https://lore.kernel.org/all/20240102210731.1f1c5bf5@gandalf.local.home/

Thanks,

-- Steve

>  path_mount+0xc24/0xfa0 fs/namespace.c:3656
>  do_mount fs/namespace.c:3677 [inline]
>  __do_sys_mount fs/namespace.c:3886 [inline]
>  __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3863
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x63/0x6b
> RIP: 0033:0x7fec326e8d99
> Code: 48 83 c4 28 c3 e8 67 17 00 00 0f 1f 80 00 00 00 00 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:00007ffc8103ddf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffc8103de00 RCX: 00007fec326e8d99
> RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000000
> RBP: 00007ffc8103de08 R08: 0000000020000140 R09: 00007fec326b5b80
> R10: 0000000002200022 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffc8103e068 R14: 0000000000000001 R15: 0000000000000001
>  </TASK>
> Modules linked in:
> CR2: fffffffffffffff0
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:set_gid fs/tracefs/inode.c:224 [inline]
> RIP: 0010:tracefs_apply_options+0x4d0/0xa40 fs/tracefs/inode.c:337
> Code: 24 10 49 8b 1e 48 83 c3 f0 74 3d 48 89 d8 48 c1 e8 03 48 bd 00 00 00 00 00 fc ff df 80 3c 28 00 74 08 48 89 df e8 70 ff 88 fe <48> 8b 1b 48 89 de 48 83 e6 02 31 ff e8 bf fe 2c fe 48 83 e3 02 75
> RSP: 0018:ffffc900040ffca8 EFLAGS: 00010246
> RAX: 1ffffffffffffffe RBX: fffffffffffffff0 RCX: ffff888014bf5940
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffc900040ffc20
> RBP: dffffc0000000000 R08: 0000000000000003 R09: fffff5200081ff84
> R10: dffffc0000000000 R11: fffff5200081ff84 R12: ffff88801d743888
> R13: ffff88801b0c3710 R14: ffff88801d7437e8 R15: ffff88801d743810
> FS:  00005555557dd480(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: fffffffffffffff0 CR3: 000000001ec48000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:	24 10                	and    $0x10,%al
>    2:	49 8b 1e             	mov    (%r14),%rbx
>    5:	48 83 c3 f0          	add    $0xfffffffffffffff0,%rbx
>    9:	74 3d                	je     0x48
>    b:	48 89 d8             	mov    %rbx,%rax
>    e:	48 c1 e8 03          	shr    $0x3,%rax
>   12:	48 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%rbp
>   19:	fc ff df
>   1c:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1)
>   20:	74 08                	je     0x2a
>   22:	48 89 df             	mov    %rbx,%rdi
>   25:	e8 70 ff 88 fe       	call   0xfe88ff9a
> * 2a:	48 8b 1b             	mov    (%rbx),%rbx <-- trapping instruction
>   2d:	48 89 de             	mov    %rbx,%rsi
>   30:	48 83 e6 02          	and    $0x2,%rsi
>   34:	31 ff                	xor    %edi,%edi
>   36:	e8 bf fe 2c fe       	call   0xfe2cfefa
>   3b:	48 83 e3 02          	and    $0x2,%rbx
>   3f:	75                   	.byte 0x75
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup