Re: [syzbot] [overlayfs?] general protection fault in ovl_init_uuid_xattr

[Amir Goldstein]

On Tue, Jul 11, 2023 at 6:32 AM syzbot
<syzbot+b592c1f562f0da80ce2c@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    123212f53f3e Add linux-next specific files for 20230707
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12353b44a80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=15ec80b62f588543
> dashboard link: https://syzkaller.appspot.com/bug?extid=b592c1f562f0da80ce2c
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15741e22a80000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1105b4e2a80000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/098f7ee2237c/disk-123212f5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/88defebbfc49/vmlinux-123212f5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/d5e9343ec16a/bzImage-123212f5.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b592c1f562f0da80ce2c@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> general protection fault, probably for non-canonical address 0xdffffc000000001c: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x00000000000000e0-0x00000000000000e7]
> CPU: 1 PID: 5024 Comm: syz-executor280 Not tainted 6.4.0-next-20230707-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
> RIP: 0010:ovl_do_getxattr fs/overlayfs/overlayfs.h:263 [inline]
> RIP: 0010:ovl_path_getxattr fs/overlayfs/overlayfs.h:292 [inline]
> RIP: 0010:ovl_init_uuid_xattr+0x1f6/0xa90 fs/overlayfs/util.c:695
> Code: c1 ea 03 80 3c 02 00 0f 85 54 08 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 74 24 08 48 8d be e0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f2 07 00 00 4c 89 e1 48 8b 86 e0 00 00 00 48 ba
> RSP: 0018:ffffc90003aafab8 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffff888014e67c00 RCX: 0000000000000005
> RDX: 000000000000001c RSI: 0000000000000000 RDI: 00000000000000e0
> RBP: ffff888029c04678 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000001 R12: ffff88801927c480
> R13: ffff888014e67c79 R14: ffff888014e67c60 R15: 0000000000000000
> FS:  0000555556b13300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001000 CR3: 0000000022580000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  ovl_fill_super+0x1f94/0x5d70 fs/overlayfs/super.c:1437
>  vfs_get_super+0xea/0x280 fs/super.c:1152
>  vfs_get_tree+0x8d/0x350 fs/super.c:1519
>  do_new_mount fs/namespace.c:3335 [inline]
>  path_mount+0x136e/0x1e70 fs/namespace.c:3662
>  do_mount fs/namespace.c:3675 [inline]
>  __do_sys_mount fs/namespace.c:3884 [inline]
>  __se_sys_mount fs/namespace.c:3861 [inline]
>  __x64_sys_mount+0x283/0x300 fs/namespace.c:3861
>  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: 0033:0x7f60c9bc0b09
> Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 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 c0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffc22c0ccf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f60c9bc0b09
> RDX: 00000000200000c0 RSI: 0000000020000200 RDI: 0000000000000000
> RBP: 00007f60c9b84cb0 R08: 0000000020000480 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f60c9b84d40
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:ovl_do_getxattr fs/overlayfs/overlayfs.h:263 [inline]
> RIP: 0010:ovl_path_getxattr fs/overlayfs/overlayfs.h:292 [inline]
> RIP: 0010:ovl_init_uuid_xattr+0x1f6/0xa90 fs/overlayfs/util.c:695
> Code: c1 ea 03 80 3c 02 00 0f 85 54 08 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 74 24 08 48 8d be e0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f2 07 00 00 4c 89 e1 48 8b 86 e0 00 00 00 48 ba
> RSP: 0018:ffffc90003aafab8 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffff888014e67c00 RCX: 0000000000000005
> RDX: 000000000000001c RSI: 0000000000000000 RDI: 00000000000000e0
> RBP: ffff888029c04678 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000001 R12: ffff88801927c480
> R13: ffff888014e67c79 R14: ffff888014e67c60 R15: 0000000000000000
> FS:  0000555556b13300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001000 CR3: 0000000022580000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:   c1 ea 03                shr    $0x3,%edx
>    3:   80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1)
>    7:   0f 85 54 08 00 00       jne    0x861
>    d:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
>   14:   fc ff df
>   17:   49 8b 74 24 08          mov    0x8(%r12),%rsi
>   1c:   48 8d be e0 00 00 00    lea    0xe0(%rsi),%rdi
>   23:   48 89 fa                mov    %rdi,%rdx
>   26:   48 c1 ea 03             shr    $0x3,%rdx
> * 2a:   80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
>   2e:   0f 85 f2 07 00 00       jne    0x826
>   34:   4c 89 e1                mov    %r12,%rcx
>   37:   48 8b 86 e0 00 00 00    mov    0xe0(%rsi),%rax
>   3e:   48                      rex.W
>   3f:   ba                      .byte 0xba
>
>
> ---
> 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@xxxxxxxxxxxxxxxx.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the bug is already fixed, 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.

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs.git
overlayfs-next