general protection fault in erofs_bread

Tue Jun 13 04:48:09 AEST 2023

Good day,

Dear Maintainers,

I found the following bug:

Kernel branch: 6.3.0-next-20230426

Kernel config: https://drive.google.com/file/d/1KU1ivdc6axWGXqmaODg5wYNJZ4v7p75j/view?usp=sharing

C reproducer: https://drive.google.com/file/d/14qxiXna1l9BLxDH2Ozo6oebnhjbNi06e/view?usp=sharing

loop4: detected capacity change from 0 to 16

erofs: (device loop4): EXPERIMENTAL compressed fragments feature in use. Use at your own risk!

erofs: (device loop4): EXPERIMENTAL global deduplication feature in use. Use at your own risk!

general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] PREEMPT SMP KASAN

KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]

CPU: 6 PID: 14033 Comm: syz-executor.4 Not tainted 6.3.0-next-20230426 #1

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014

RIP: 0010:erofs_bread+0x56/0x6d0 fs/erofs/data.c:38

Code: 48 c1 ea 03 80 3c 02 00 0f 85 17 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 8d bc 24 ca 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 84 05 00 00

RSP: 0018:ffffc90003f9f980 EFLAGS: 00010212

RAX: dffffc0000000000 RBX: ffffc90003f9faf8 RCX: ffffc9001350c000

RDX: 0000000000000019 RSI: ffffffff83b7198f RDI: 00000000000000ca

RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000003f

R10: 000000000000000c R11: 000000000008c001 R12: 0000000000000000

R13: 0000000000000001 R14: ffff888079bfa000 R15: ffff888079bfa000

FS:  00007f5338e33700(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000

CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f5337c61c40 CR3: 0000000045e57000 CR4: 0000000000350ee0

Call Trace:

 <TASK>

 erofs_read_metadata+0xbb/0x490 fs/erofs/super.c:137

 erofs_xattr_prefixes_init+0x3b1/0x590 fs/erofs/xattr.c:684

 erofs_fc_fill_super+0x1732/0x2a70 fs/erofs/super.c:825

 get_tree_bdev+0x44a/0x770 fs/super.c:1303

 vfs_get_tree+0x8d/0x350 fs/super.c:1510

 do_new_mount fs/namespace.c:3039 [inline]

 path_mount+0x675/0x1e30 fs/namespace.c:3369

 do_mount fs/namespace.c:3382 [inline]

 __do_sys_mount fs/namespace.c:3591 [inline]

 __se_sys_mount fs/namespace.c:3568 [inline]

 __x64_sys_mount+0x283/0x300 fs/namespace.c:3568

 do_syscall_x64 arch/x86/entry/common.c:50 [inline]

 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:80

 entry_SYSCALL_64_after_hwframe+0x63/0xcd

RIP: 0033:0x7f5337c9176e

Code: 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 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:00007f5338e32a08 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5

RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f5337c9176e

RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f5338e32a60

RBP: 00007f5338e32aa0 R08: 00007f5338e32aa0 R09: 0000000020000000

R10: 0000000000000000 R11: 0000000000000206 R12: 0000000020000000

R13: 0000000020000100 R14: 00007f5338e32a60 R15: 00000000200108a0

 </TASK>

Modules linked in:

---[ end trace 0000000000000000 ]---

RIP: 0010:erofs_bread+0x56/0x6d0 fs/erofs/data.c:38

Code: 48 c1 ea 03 80 3c 02 00 0f 85 17 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 8d bc 24 ca 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 84 05 00 00

RSP: 0018:ffffc90003f9f980 EFLAGS: 00010212

RAX: dffffc0000000000 RBX: ffffc90003f9faf8 RCX: ffffc9001350c000

RDX: 0000000000000019 RSI: ffffffff83b7198f RDI: 00000000000000ca

RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000003f

R10: 000000000000000c R11: 000000000008c001 R12: 0000000000000000

R13: 0000000000000001 R14: ffff888079bfa000 R15: ffff888079bfa000

FS:  00007f5338e33700(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000

CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f5337c61c40 CR3: 0000000045e57000 CR4: 0000000000350ee0

----------------

Code disassembly (best guess):

   0:   48 c1 ea 03             shr    $0x3,%rdx

   4:   80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1)

   8:   0f 85 17 06 00 00       jne    0x625

   e:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax

  15:   fc ff df

  18:   4c 8b 23                mov    (%rbx),%r12

  1b:   49 8d bc 24 ca 00 00    lea    0xca(%r12),%rdi

  22:   00

  23:   48 89 fa                mov    %rdi,%rdx

  26:   48 c1 ea 03             shr    $0x3,%rdx

* 2a:   0f b6 04 02             movzbl (%rdx,%rax,1),%eax <-- trapping instruction

  2e:   48 89 fa                mov    %rdi,%rdx

  31:   83 e2 07                and    $0x7,%edx

  34:   38 d0                   cmp    %dl,%al

  36:   7f 08                   jg     0x40

  38:   84 c0                   test   %al,%al

  3a:   0f 85 84 05 00 00       jne    0x5c4

Thank you very much!

Best Regards,

[Block U Logo]  Khagan Karimov (He/His/Him)
Ph.D. student | Security Researcher
Kahlert School of Computing, The University of Utah
meritpages.com/khagan_karimov
khagan.net

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