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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Wed, 13 Sep 2023 10:09:48 +0300
Message-ID: <CAOQ4uxjBAG-WA+1VCdYh6O98mU3C31qMyZZFp3iRW6_yYROdWQ@mail.gmail.com>
Subject: Re: [syzbot] [overlayfs?] general protection fault in d_path
To:     syzbot <syzbot+a67fc5321ffb4b311c98@syzkaller.appspotmail.com>
Cc:     brauner@kernel.org, jlayton@kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-unionfs@vger.kernel.org, miklos@szeredi.hu,
        syzkaller-bugs@googlegroups.com, zohar@linux.ibm.com
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On Wed, Sep 13, 2023 at 1:10=E2=80=AFAM syzbot
<syzbot+a67fc5321ffb4b311c98@syzkaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit:    a747acc0b752 Merge tag 'linux-kselftest-next-6.6-rc2' of =
g..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=3D11c8230868000=
0
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3Ddf91a3034fe3f=
122
> dashboard link: https://syzkaller.appspot.com/bug?extid=3Da67fc5321ffb4b3=
11c98
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Deb=
ian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=3D1671b694680=
000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=3D14ec94d868000=
0
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/b28ecb88c714/dis=
k-a747acc0.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/03dd2cd5356f/vmlinu=
x-a747acc0.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/63365d9bf980/b=
zImage-a747acc0.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the comm=
it:
> Reported-by: syzbot+a67fc5321ffb4b311c98@syzkaller.appspotmail.com
>
> general protection fault, probably for non-canonical address 0xdffffc0000=
000009: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
> CPU: 0 PID: 5030 Comm: syz-executor173 Not tainted 6.6.0-rc1-syzkaller-00=
014-ga747acc0b752 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS G=
oogle 08/04/2023
> RIP: 0010:__seqprop_spinlock_sequence include/linux/seqlock.h:275 [inline=
]
> RIP: 0010:get_fs_root_rcu fs/d_path.c:244 [inline]
> RIP: 0010:d_path+0x2f0/0x6e0 fs/d_path.c:286
> Code: 30 00 74 08 48 89 df e8 be 20 e1 ff 4c 8b 23 4d 8d 6c 24 48 49 81 c=
4 88 00 00 00 4c 89 eb 48 c1 eb 03 4c 89 ef e8 00 1e 00 00 <42> 0f b6 04 33=
 84 c0 0f 85 89 00 00 00 45 8b 7d 00 44 89 fe 83 e6
> RSP: 0018:ffffc90003a7eee0 EFLAGS: 00010246
> RAX: 7e73051ae5315e00 RBX: 0000000000000009 RCX: ffff88807da73b80
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffffc90003a7eff0 R08: ffffffff82068d08 R09: 1ffffffff1d34ccd
> R10: dffffc0000000000 R11: fffffbfff1d34cce R12: 0000000000000088
> R13: 0000000000000048 R14: dffffc0000000000 R15: ffff8880206d8000
> FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000=
000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f351862ebb8 CR3: 00000000276a7000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  audit_log_d_path+0xd3/0x310 kernel/audit.c:2138
>  dump_common_audit_data security/lsm_audit.c:224 [inline]
>  common_lsm_audit+0x7cf/0x1a90 security/lsm_audit.c:458
>  smack_log+0x421/0x540 security/smack/smack_access.c:383
>  smk_tskacc+0x2ff/0x360 security/smack/smack_access.c:253
>  smack_inode_getattr+0x203/0x270 security/smack/smack_lsm.c:1271
>  security_inode_getattr+0xd3/0x120 security/security.c:2153
>  vfs_getattr+0x2a/0x3a0 fs/stat.c:206
>  ovl_getattr+0x1b1/0xf70 fs/overlayfs/inode.c:174
>  ima_check_last_writer security/integrity/ima/ima_main.c:171 [inline]
>  ima_file_free+0x26e/0x4b0 security/integrity/ima/ima_main.c:203
>  __fput+0x36a/0x910 fs/file_table.c:378
>  task_work_run+0x24a/0x300 kernel/task_work.c:179
>  exit_task_work include/linux/task_work.h:38 [inline]
>  do_exit+0x68f/0x2290 kernel/exit.c:874
>  do_group_exit+0x206/0x2c0 kernel/exit.c:1024
>  get_signal+0x175d/0x1840 kernel/signal.c:2892
>  arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:309
>  exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:168
>  exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
>  syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:296
>  do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f35185d8529
> Code: Unable to access opcode bytes at 0x7f35185d84ff.
> RSP: 002b:00007f3518599218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: 0000000000000001 RBX: 00007f3518662308 RCX: 00007f35185d8529
> RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f351866230c
> RBP: 00007f3518662300 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f351862f064
> R13: 0031656c69662f2e R14: 6e6f3d7865646e69 R15: 0079616c7265766f
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__seqprop_spinlock_sequence include/linux/seqlock.h:275 [inline=
]
> RIP: 0010:get_fs_root_rcu fs/d_path.c:244 [inline]
> RIP: 0010:d_path+0x2f0/0x6e0 fs/d_path.c:286
> Code: 30 00 74 08 48 89 df e8 be 20 e1 ff 4c 8b 23 4d 8d 6c 24 48 49 81 c=
4 88 00 00 00 4c 89 eb 48 c1 eb 03 4c 89 ef e8 00 1e 00 00 <42> 0f b6 04 33=
 84 c0 0f 85 89 00 00 00 45 8b 7d 00 44 89 fe 83 e6
> RSP: 0018:ffffc90003a7eee0 EFLAGS: 00010246
> RAX: 7e73051ae5315e00 RBX: 0000000000000009 RCX: ffff88807da73b80
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffffc90003a7eff0 R08: ffffffff82068d08 R09: 1ffffffff1d34ccd
> R10: dffffc0000000000 R11: fffffbfff1d34cce R12: 0000000000000088
> R13: 0000000000000048 R14: dffffc0000000000 R15: ffff8880206d8000
> FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000=
000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f351862ebb8 CR3: 000000007e769000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:   30 00                   xor    %al,(%rax)
>    2:   74 08                   je     0xc
>    4:   48 89 df                mov    %rbx,%rdi
>    7:   e8 be 20 e1 ff          call   0xffe120ca
>    c:   4c 8b 23                mov    (%rbx),%r12
>    f:   4d 8d 6c 24 48          lea    0x48(%r12),%r13
>   14:   49 81 c4 88 00 00 00    add    $0x88,%r12
>   1b:   4c 89 eb                mov    %r13,%rbx
>   1e:   48 c1 eb 03             shr    $0x3,%rbx
>   22:   4c 89 ef                mov    %r13,%rdi
>   25:   e8 00 1e 00 00          call   0x1e2a
> * 2a:   42 0f b6 04 33          movzbl (%rbx,%r14,1),%eax <-- trapping in=
struction
>   2f:   84 c0                   test   %al,%al
>   31:   0f 85 89 00 00 00       jne    0xc0
>   37:   45 8b 7d 00             mov    0x0(%r13),%r15d
>   3b:   44 89 fe                mov    %r15d,%esi
>   3e:   83                      .byte 0x83
>   3f:   e6                      .byte 0xe6
>
>
> ---
> 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 set subsystems: integrity, overlayfs

#syz test: https://github.com/amir73il/linux ima-ovl-fix