[syzbot] [lsm?] general protection fault in hook_inode_free_security

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dccb07f2914c Merge tag 'for-6.9-rc7-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14a46760980000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d14c12b661fb43
dashboard link: https://syzkaller.appspot.com/bug?extid=5446fbf332b0602ede0b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/39d66018d8ad/disk-dccb07f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c160b651d1bc/vmlinux-dccb07f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3662a33ac713/bzImage-dccb07f2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5446fb...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc018f62f515: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: probably user-memory-access in range [0x0000000c7b17a8a8-0x0000000c7b17a8af]
CPU: 1 PID: 5102 Comm: syz-executor.1 Not tainted 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:hook_inode_free_security+0x5b/0xb0 security/landlock/fs.c:1047
Code: 8a fd 48 8b 1b 48 c7 c0 c4 4e d5 8d 48 c1 e8 03 42 0f b6 04 30 84 c0 75 3e 48 63 05 33 59 65 09 48 01 c3 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 66 be 8a fd 48 83 3b 00 75 0d e8
RSP: 0018:ffffc9000307f9a8 EFLAGS: 00010212
RAX: 000000018f62f515 RBX: 0000000c7b17a8a8 RCX: ffff888027668000
RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff88805c0bb270
RBP: ffffffff8c01fb00 R08: ffffffff82132a15 R09: 1ffff1100b81765f
R10: dffffc0000000000 R11: ffffffff846ff540 R12: dffffc0000000000
R13: 1ffff1100b817683 R14: dffffc0000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f43c42de000 CR3: 00000000635f8000 CR4: 0000000000350ef0
Call Trace:
<TASK>
security_inode_free+0x4a/0xd0 security/security.c:1613
__destroy_inode+0x2d9/0x650 fs/inode.c:286
destroy_inode fs/inode.c:309 [inline]
evict+0x521/0x630 fs/inode.c:682
dispose_list fs/inode.c:700 [inline]
evict_inodes+0x5f9/0x690 fs/inode.c:750
generic_shutdown_super+0x9d/0x2d0 fs/super.c:626
kill_block_super+0x44/0x90 fs/super.c:1675
deactivate_locked_super+0xc6/0x130 fs/super.c:472
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1267
task_work_run+0x251/0x310 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xa1b/0x27e0 kernel/exit.c:878
do_group_exit+0x207/0x2c0 kernel/exit.c:1027
__do_sys_exit_group kernel/exit.c:1038 [inline]
__se_sys_exit_group kernel/exit.c:1036 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1036
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f731567dd69
Code: Unable to access opcode bytes at 0x7f731567dd3f.
RSP: 002b:00007fff4f0804d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f73156c93a3 RCX: 00007f731567dd69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000002 R08: 00007fff4f07e277 R09: 00007fff4f081790
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff4f081790
R13: 00007f73156c937e R14: 00000000000154d0 R15: 000000000000001e
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hook_inode_free_security+0x5b/0xb0 security/landlock/fs.c:1047
Code: 8a fd 48 8b 1b 48 c7 c0 c4 4e d5 8d 48 c1 e8 03 42 0f b6 04 30 84 c0 75 3e 48 63 05 33 59 65 09 48 01 c3 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 66 be 8a fd 48 83 3b 00 75 0d e8
RSP: 0018:ffffc9000307f9a8 EFLAGS: 00010212
RAX: 000000018f62f515 RBX: 0000000c7b17a8a8 RCX: ffff888027668000
RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff88805c0bb270
RBP: ffffffff8c01fb00 R08: ffffffff82132a15 R09: 1ffff1100b81765f
R10: dffffc0000000000 R11: ffffffff846ff540 R12: dffffc0000000000
R13: 1ffff1100b817683 R14: dffffc0000000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555587f03978 CR3: 0000000049876000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
0: 8a fd mov %ch,%bh
2: 48 8b 1b mov (%rbx),%rbx
5: 48 c7 c0 c4 4e d5 8d mov $0xffffffff8dd54ec4,%rax
c: 48 c1 e8 03 shr $0x3,%rax
10: 42 0f b6 04 30 movzbl (%rax,%r14,1),%eax
15: 84 c0 test %al,%al
17: 75 3e jne 0x57
19: 48 63 05 33 59 65 09 movslq 0x9655933(%rip),%rax # 0x9655953
20: 48 01 c3 add %rax,%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 48 89 df mov %rbx,%rdi
34: e8 66 be 8a fd call 0xfd8abe9f
39: 48 83 3b 00 cmpq $0x0,(%rbx)
3d: 75 0d jne 0x4c
3f: e8 .byte 0xe8


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[Paul Moore]

On Wed, May 8, 2024 at 3:32 PM syzbot
<syzbot+5446fb...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: dccb07f2914c Merge tag 'for-6.9-rc7-tag' of git://git.kern..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14a46760980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=6d14c12b661fb43
> dashboard link: https://syzkaller.appspot.com/bug?extid=5446fbf332b0602ede0b
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/39d66018d8ad/disk-dccb07f2.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/c160b651d1bc/vmlinux-dccb07f2.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/3662a33ac713/bzImage-dccb07f2.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5446fb...@syzkaller.appspotmail.com
>
> general protection fault, probably for non-canonical address 0xdffffc018f62f515: 0000 [#1] PREEMPT SMP KASAN NOPTI
> KASAN: probably user-memory-access in range [0x0000000c7b17a8a8-0x0000000c7b17a8af]
> CPU: 1 PID: 5102 Comm: syz-executor.1 Not tainted 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
> RIP: 0010:hook_inode_free_security+0x5b/0xb0 security/landlock/fs.c:1047

Possibly a Landlock issue, Mickaël?

--
paul-moore.com

[Mickaël Salaün]

On Thu, May 09, 2024 at 08:01:49PM -0400, Paul Moore wrote:
> On Wed, May 8, 2024 at 3:32 PM syzbot
> <syzbot+5446fb...@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: dccb07f2914c Merge tag 'for-6.9-rc7-tag' of git://git.kern..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14a46760980000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=6d14c12b661fb43
> > dashboard link: https://syzkaller.appspot.com/bug?extid=5446fbf332b0602ede0b
> > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/39d66018d8ad/disk-dccb07f2.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/c160b651d1bc/vmlinux-dccb07f2.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/3662a33ac713/bzImage-dccb07f2.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+5446fb...@syzkaller.appspotmail.com
> >
> > general protection fault, probably for non-canonical address 0xdffffc018f62f515: 0000 [#1] PREEMPT SMP KASAN NOPTI
> > KASAN: probably user-memory-access in range [0x0000000c7b17a8a8-0x0000000c7b17a8af]
> > CPU: 1 PID: 5102 Comm: syz-executor.1 Not tainted 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
> > RIP: 0010:hook_inode_free_security+0x5b/0xb0 security/landlock/fs.c:1047
>
> Possibly a Landlock issue, Mickaël?

It looks like security_inode_free() is called two times on the same
inode. This could happen if an inode labeled by Landlock is put
concurrently with release_inode() for a closed ruleset or with
hook_sb_delete(). I didn't find any race condition that could lead to
two calls to iput() though. Could WRITE_ONCE(object->underobj, NULL)
change anything even if object->lock is locked?

A bit unrelated but looking at the SELinux code, I see that selinux_inode()
checks `!inode->i_security`. In which case could this happen?

[Mickaël Salaün]

Adding membarrier experts.

[Mathieu Desnoyers]

On 2024-05-16 03:31, Mickaël Salaün wrote:
> Adding membarrier experts.

I do not see how this relates to the membarrier(2) system call.

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com