linux-kernel - BUG: unable to handle kernel paging request in do

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Message-ID: <b4f743e5-ad5b-48cf-827b-e3da9bb448a2.bugreport@ubisectech.com>
Date: Tue, 30 Apr 2024 09:16:50 +0800
From: "Ubisectech Sirius" <bugreport@...sectech.com>
To: "linux-trace-kernel" <linux-trace-kernel@...r.kernel.org>,
  "linux-kernel" <linux-kernel@...r.kernel.org>
Cc: "tytso" <tytso@....edu>,
  "adilger.kernel" <adilger.kernel@...ger.ca>
Subject: BUG: unable to handle kernel paging request in do_split

Hello.
We are Ubisectech Sirius Team, the vulnerability lab of China ValiantSec. Recently, our team has discovered a issue in Linux kernel 6.7. Attached to the email were a PoC file of the issue.

Stack dump:
BUG: unable to handle page fault for address: ffffed110c2fd97f
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 7ffd0067 P4D 7ffd0067 PUD 0
Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 PID: 24082 Comm: syz-executor.3 Not tainted 6.7.0 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:do_split+0xfef/0x1e10 fs/ext4/namei.c:2047
Code: d2 0f 85 38 0b 00 00 8b 45 00 89 84 24 84 00 00 00 41 8d 45 ff 48 8d 1c c3 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 ef
RSP: 0018:ffffc90001e9f858 EFLAGS: 00010a02
RAX: dffffc0000000000 RBX: ffff8888617ecbf8 RCX: ffffc9001048f000
RDX: 1ffff1110c2fd97f RSI: ffffffff823364ab RDI: 0000000000000005
RBP: ffff8880617ecc00 R08: 0000000000000005 R09: 00000000ffffffff
R10: 00000000ffffffff R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: 00000000ffffffff R15: ffff88801ee8d2b0
FS:  00007f191402a640(0000) GS:ffff88802c600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed110c2fd97f CR3: 000000005500a000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 make_indexed_dir+0x1158/0x1540 fs/ext4/namei.c:2342
 ext4_add_entry+0xcd0/0xe80 fs/ext4/namei.c:2454
 ext4_add_nondir+0x90/0x2b0 fs/ext4/namei.c:2795
 ext4_symlink+0x539/0x9e0 fs/ext4/namei.c:3436
 vfs_symlink fs/namei.c:4464 [inline]
 vfs_symlink+0x3f6/0x640 fs/namei.c:4448
 do_symlinkat+0x245/0x2f0 fs/namei.c:4490
 __do_sys_symlink fs/namei.c:4511 [inline]
 __se_sys_symlink fs/namei.c:4509 [inline]
 __x64_sys_symlink+0x79/0xa0 fs/namei.c:4509
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x43/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f191329002d
Code: c3 e8 97 2b 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 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:00007f191402a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00007f19133cbf80 RCX: 00007f191329002d
RDX: 0000000000000000 RSI: 0000000020000e40 RDI: 0000000020001640
RBP: 00007f19132f14d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f19133cbf80 R15: 00007f191400a000
 </TASK>
Modules linked in:
CR2: ffffed110c2fd97f
---[ end trace 0000000000000000 ]---
RIP: 0010:do_split+0xfef/0x1e10 fs/ext4/namei.c:2047
Code: d2 0f 85 38 0b 00 00 8b 45 00 89 84 24 84 00 00 00 41 8d 45 ff 48 8d 1c c3 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 ef
RSP: 0018:ffffc90001e9f858 EFLAGS: 00010a02
RAX: dffffc0000000000 RBX: ffff8888617ecbf8 RCX: ffffc9001048f000
RDX: 1ffff1110c2fd97f RSI: ffffffff823364ab RDI: 0000000000000005
RBP: ffff8880617ecc00 R08: 0000000000000005 R09: 00000000ffffffff
R10: 00000000ffffffff R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: 00000000ffffffff R15: ffff88801ee8d2b0
FS:  00007f191402a640(0000) GS:ffff88802c600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed110c2fd97f CR3: 000000005500a000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
----------------
Code disassembly (best guess):
   0:   d2 0f                   rorb   %cl,(%rdi)
   2:   85 38                   test   %edi,(%rax)
   4:   0b 00                   or     (%rax),%eax
   6:   00 8b 45 00 89 84       add    %cl,-0x7b76ffbb(%rbx)
   c:   24 84                   and    $0x84,%al
   e:   00 00                   add    %al,(%rax)
  10:   00 41 8d                add    %al,-0x73(%rcx)
  13:   45 ff 48 8d             rex.RB decl -0x73(%r8)
  17:   1c c3                   sbb    $0xc3,%al
  19:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
  20:   fc ff df
  23:   48 89 da                mov    %rbx,%rdx
  26:   48 c1 ea 03             shr    $0x3,%rdx
* 2a:   0f b6 14 02             movzbl (%rdx,%rax,1),%edx <-- trapping instruction
  2e:   48 89 d8                mov    %rbx,%rax
  31:   83 e0 07                and    $0x7,%eax
  34:   83 c0 03                add    $0x3,%eax
  37:   38 d0                   cmp    %dl,%al
  39:   7c 08                   jl     0x43
  3b:   84 d2                   test   %dl,%dl
  3d:   0f                      .byte 0xf
  3e:   85 ef                   test   %ebp,%edi


Thank you for taking the time to read this email and we look forward to working with you further.











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