[syzbot] [fscrypt?] WARNING in fscrypt_destroy_keyring

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fe15c26ee26e Linux 6.3-rc1
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=14e2d88ac80000
kernel config: https://syzkaller.appspot.com/x/.config?x=7573cbcd881a88c9
dashboard link: https://syzkaller.appspot.com/bug?extid=93e495f6a4f748827c88
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16171188c80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15ac08dac80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/89d41abd07bd/disk-fe15c26e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fa75f5030ade/vmlinux-fe15c26e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/590d0f5903ee/Image-fe15c26e.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/bf3b409baf10/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+93e495...@syzkaller.appspotmail.com

EXT4-fs (loop0): mounted filesystem 76b65be2-f6da-4727-8c75-0525a5b65a09 without journal. Quota mode: writeback.
fscrypt: AES-256-CTS-CBC using implementation "cts-cbc-aes-ce"
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5945 at fs/crypto/keyring.c:237 fscrypt_destroy_keyring+0x164/0x240 fs/crypto/keyring.c:237
Modules linked in:
CPU: 1 PID: 5945 Comm: syz-executor265 Not tainted 6.3.0-rc1-syzkaller-gfe15c26ee26e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : fscrypt_destroy_keyring+0x164/0x240 fs/crypto/keyring.c:237
lr : fscrypt_destroy_keyring+0x164/0x240 fs/crypto/keyring.c:237
sp : ffff80001e4c7960
x29: ffff80001e4c7960 x28: 1fffe0001aaec0fa x27: 0000000000000000
x26: 0000000000000073 x25: 1fffe00019138025 x24: dfff800000000000
x23: 0000000000000002 x22: ffff0000cbffa000 x21: ffff0000c738e000
x20: ffff0000c89c0000 x19: ffff0000c89c0128 x18: ffff80001e4c7320
x17: ffff800015cdd000 x16: ffff800008313a3c x15: ffff8000081cd8e0
x14: 1ffff00002b9c0b2 x13: dfff800000000000 x12: 0000000000000001
x11: ff80800008bcd61c x10: 0000000000000000 x9 : ffff800008bcd61c
x8 : ffff0000cc0b3680 x7 : ffff800008b76ab4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800008bcd558
x2 : 0000000000000000 x1 : 0000000000000002 x0 : 0000000000000001
Call trace:
fscrypt_destroy_keyring+0x164/0x240 fs/crypto/keyring.c:237
generic_shutdown_super+0xac/0x328 fs/super.c:482
kill_block_super+0x70/0xdc fs/super.c:1398
deactivate_locked_super+0xac/0x124 fs/super.c:331
deactivate_super+0xf0/0x110 fs/super.c:362
cleanup_mnt+0x34c/0x3dc fs/namespace.c:1177
__cleanup_mnt+0x20/0x30 fs/namespace.c:1184
task_work_run+0x240/0x2f0 kernel/task_work.c:179
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x4fc/0x1a30 kernel/exit.c:869
do_group_exit+0x194/0x22c kernel/exit.c:1019
__do_sys_exit_group kernel/exit.c:1030 [inline]
__se_sys_exit_group kernel/exit.c:1028 [inline]
__wake_up_parent+0x0/0x60 kernel/exit.c:1028
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
irq event stamp: 16114
hardirqs last enabled at (16113): [<ffff8000083af01c>] __call_rcu_common kernel/rcu/tree.c:2658 [inline]
hardirqs last enabled at (16113): [<ffff8000083af01c>] call_rcu+0x65c/0xb38 kernel/rcu/tree.c:2736
hardirqs last disabled at (16114): [<ffff80001245e098>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last enabled at (15276): [<ffff800008020ec0>] softirq_handle_end kernel/softirq.c:414 [inline]
softirqs last enabled at (15276): [<ffff800008020ec0>] __do_softirq+0xd64/0xfbc kernel/softirq.c:600
softirqs last disabled at (15265): [<ffff80000802b524>] ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
---[ end trace 0000000000000000 ]---
Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 5945 Comm: syz-executor265 Tainted: G W 6.3.0-rc1-syzkaller-gfe15c26ee26e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __lock_acquire+0x104/0x764c kernel/locking/lockdep.c:4926
lr : lock_acquire+0x2f0/0x8c8 kernel/locking/lockdep.c:5669
sp : ffff80001e4c7040
x29: ffff80001e4c72e0 x28: 1ffff00002b9c0b1 x27: ffff800008bcd13c
x26: 0000000000000001 x25: ffff700003c98e2c x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000000000 x19: 0000000000000018 x18: ffff80001e4c7398
x17: ffff800015cdd000 x16: ffff80001246263c x15: ffff8000081cd8e0
x14: 1ffff00002b9c0b2 x13: ffff80001e4c7160 x12: dfff800000000000
x11: ffff800008318d80 x10: ffff800015ce058c x9 : 00000000000000f3
x8 : 0000000000000003 x7 : ffff800008bcd13c x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000018
Call trace:
__lock_acquire+0x104/0x764c kernel/locking/lockdep.c:4926
lock_acquire+0x2f0/0x8c8 kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
fscrypt_put_master_key_activeref+0x8c/0x408 fs/crypto/keyring.c:95
put_crypt_info+0x218/0x2d0 fs/crypto/keysetup.c:546
fscrypt_put_encryption_info+0x44/0x6c fs/crypto/keysetup.c:743
ext4_clear_inode+0x154/0x1a0 fs/ext4/super.c:1445
ext4_evict_inode+0x6ec/0x148c fs/ext4/inode.c:346
evict+0x260/0x68c fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput+0x988/0xa6c fs/inode.c:1774
hook_sb_delete+0x688/0xa10 security/landlock/fs.c:1025
security_sb_delete+0x50/0x94 security/security.c:950
generic_shutdown_super+0xb4/0x328 fs/super.c:483
kill_block_super+0x70/0xdc fs/super.c:1398
deactivate_locked_super+0xac/0x124 fs/super.c:331
deactivate_super+0xf0/0x110 fs/super.c:362
cleanup_mnt+0x34c/0x3dc fs/namespace.c:1177
__cleanup_mnt+0x20/0x30 fs/namespace.c:1184
task_work_run+0x240/0x2f0 kernel/task_work.c:179
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x4fc/0x1a30 kernel/exit.c:869
do_group_exit+0x194/0x22c kernel/exit.c:1019
__do_sys_exit_group kernel/exit.c:1030 [inline]
__se_sys_exit_group kernel/exit.c:1028 [inline]
__wake_up_parent+0x0/0x60 kernel/exit.c:1028
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
Code: d006d368 b9482108 34000208 d343fe68 (386c6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: d006d368 adrp x8, 0xda6e000
4: b9482108 ldr w8, [x8, #2080]
8: 34000208 cbz w8, 0x48
c: d343fe68 lsr x8, x19, #3
* 10: 386c6908 ldrb w8, [x8, x12] <-- trapping instruction


---
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syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Eric Biggers]

On Mon, Mar 13, 2023 at 08:53:55AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: fe15c26ee26e Linux 6.3-rc1
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=14e2d88ac80000
> kernel config: https://syzkaller.appspot.com/x/.config?x=7573cbcd881a88c9
> dashboard link: https://syzkaller.appspot.com/bug?extid=93e495f6a4f748827c88
> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16171188c80000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15ac08dac80000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/89d41abd07bd/disk-fe15c26e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/fa75f5030ade/vmlinux-fe15c26e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/590d0f5903ee/Image-fe15c26e.gz.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/bf3b409baf10/mount_0.gz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+93e495...@syzkaller.appspotmail.com
>
> EXT4-fs (loop0): mounted filesystem 76b65be2-f6da-4727-8c75-0525a5b65a09 without journal. Quota mode: writeback.
> fscrypt: AES-256-CTS-CBC using implementation "cts-cbc-aes-ce"
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 5945 at fs/crypto/keyring.c:237 fscrypt_destroy_keyring+0x164/0x240 fs/crypto/keyring.c:237

Very impressive find by syzbot! fscrypt_destroy_keyring() needs to be called
after security_sb_delete(), not before. Fix is
https://lore.kernel.org/linux-fscrypt/20230313221231.2...@kernel.org

- Eric

[Hillf Danton]

On 13 Mar 2023 08:53:55 -0700

> HEAD commit: fe15c26ee26e Linux 6.3-rc1
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15ac08dac80000

Destroy keyring after deleting super.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git fe15c26ee26e

--- x/fs/super.c
+++ y/fs/super.c
@@ -479,8 +479,8 @@ void generic_shutdown_super(struct super
evict_inodes(sb);
/* only nonzero refcount inodes can have marks */
fsnotify_sb_delete(sb);
- fscrypt_destroy_keyring(sb);
security_sb_delete(sb);
+ fscrypt_destroy_keyring(sb);

if (sb->s_dio_done_wq) {
destroy_workqueue(sb->s_dio_done_wq);
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+93e495...@syzkaller.appspotmail.com

Tested on:

commit: fe15c26e Linux 6.3-rc1
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=116c0c3ac80000

kernel config: https://syzkaller.appspot.com/x/.config?x=7573cbcd881a88c9
dashboard link: https://syzkaller.appspot.com/bug?extid=93e495f6a4f748827c88
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=12aad472c80000

Note: testing is done by a robot and is best-effort only.