* Re: [syzbot] possible deadlock in mnt_want_write (2)
[not found] ` <c75858662b90592ae3f3ab57d4500381a28bafe5.camel@linux.ibm.com>
@ 2022-07-06 12:10 ` Hillf Danton
2022-07-06 22:24 ` Mimi Zohar
0 siblings, 1 reply; 2+ messages in thread
From: Hillf Danton @ 2022-07-06 12:10 UTC (permalink / raw)
To: Mimi Zohar
Cc: syzbot, linux-fsdevel, linux-mm, linux-integrity, linux-kernel,
miklos, syzkaller-bugs, syzbot, Amir Goldstein, Hillf Danton
On Tue, 05 Jul 2022 08:53:15 -0400 Mimi Zohar wrote:
>
> Thank you for the reproducer. This seems to be a similar false
> positive as was discussed:
> https://lore.kernel.org/linux-unionfs/000000000000c5b77105b4c3546e@google.com/
>
> thanks,
>
Hi Mimi
Please pick up the patch attached if it makes sense to you.
Hillf
>
> On Sat, 2022-07-02 at 10:27 -0700, syzbot wrote:
> > syzbot has found a reproducer for the following issue on:
> >
> > HEAD commit: 089866061428 Merge tag 'libnvdimm-fixes-5.19-rc5' of git:/..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11dd91f0080000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=75c9ff14e1db87c0
> > dashboard link: https://syzkaller.appspot.com/bug?extid=b42fe626038981fb7bfa
> > compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167bafc0080000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11aad3e0080000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+b42fe626038981fb7bfa@syzkaller.appspotmail.com
> >
> > ======================================================
> > WARNING: possible circular locking dependency detected
> > 5.19.0-rc4-syzkaller-00187-g089866061428 #0 Not tainted
> > ------------------------------------------------------
> > syz-executor450/3829 is trying to acquire lock:
> > ffff88807e574460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
> >
> > but task is already holding lock:
> > ffff888074de91a0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x7d2/0x1c10 security/integrity/ima/ima_main.c:260
> >
> > which lock already depends on the new lock.
> >
> >
> > the existing dependency chain (in reverse order) is:
> >
> > -> #1 (&iint->mutex){+.+.}-{3:3}:
> > lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5665
> > __mutex_lock_common+0x1de/0x26c0 kernel/locking/mutex.c:603
> > __mutex_lock kernel/locking/mutex.c:747 [inline]
> > mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
> > process_measurement+0x7d2/0x1c10 security/integrity/ima/ima_main.c:260
> > ima_file_check+0xe7/0x160 security/integrity/ima/ima_main.c:517
> > do_open fs/namei.c:3522 [inline]
> > path_openat+0x2705/0x2ec0 fs/namei.c:3653
> > do_filp_open+0x277/0x4f0 fs/namei.c:3680
> > do_sys_openat2+0x13b/0x500 fs/open.c:1278
> > do_sys_open fs/open.c:1294 [inline]
> > __do_sys_open fs/open.c:1302 [inline]
> > __se_sys_open fs/open.c:1298 [inline]
> > __x64_sys_open+0x221/0x270 fs/open.c:1298
> > do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> > do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
> > entry_SYSCALL_64_after_hwframe+0x46/0xb0
> >
> > -> #0 (sb_writers#4){.+.+}-{0:0}:
> > check_prev_add kernel/locking/lockdep.c:3095 [inline]
> > check_prevs_add kernel/locking/lockdep.c:3214 [inline]
> > validate_chain+0x185c/0x65c0 kernel/locking/lockdep.c:3829
> > __lock_acquire+0x129a/0x1f80 kernel/locking/lockdep.c:5053
> > lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5665
> > percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
> > __sb_start_write include/linux/fs.h:1699 [inline]
> > sb_start_write+0x4d/0x1a0 include/linux/fs.h:1774
> > mnt_want_write+0x3b/0x80 fs/namespace.c:393
> > ovl_maybe_copy_up+0x124/0x190 fs/overlayfs/copy_up.c:1078
> > ovl_open+0x106/0x2a0 fs/overlayfs/file.c:152
> > do_dentry_open+0x789/0x1040 fs/open.c:848
> > vfs_open fs/open.c:981 [inline]
> > dentry_open+0xc1/0x120 fs/open.c:997
> > ima_calc_file_hash+0x157/0x1cb0 security/integrity/ima/ima_crypto.c:557
> > ima_collect_measurement+0x3de/0x850 security/integrity/ima/ima_api.c:292
> > process_measurement+0xf87/0x1c10 security/integrity/ima/ima_main.c:337
> > ima_file_check+0xe7/0x160 security/integrity/ima/ima_main.c:517
> > do_open fs/namei.c:3522 [inline]
> > path_openat+0x2705/0x2ec0 fs/namei.c:3653
> > do_filp_open+0x277/0x4f0 fs/namei.c:3680
> > do_sys_openat2+0x13b/0x500 fs/open.c:1278
> > do_sys_open fs/open.c:1294 [inline]
> > __do_sys_open fs/open.c:1302 [inline]
> > __se_sys_open fs/open.c:1298 [inline]
> > __x64_sys_open+0x221/0x270 fs/open.c:1298
> > do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> > do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
> > entry_SYSCALL_64_after_hwframe+0x46/0xb0
> >
> > other info that might help us debug this:
> >
> > Possible unsafe locking scenario:
> >
> > CPU0 CPU1
> > ---- ----
> > lock(&iint->mutex);
> > lock(sb_writers#4);
> > lock(&iint->mutex);
> > lock(sb_writers#4);
> >
> > *** DEADLOCK ***
> >
> > 1 lock held by syz-executor450/3829:
> > #0: ffff888074de91a0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x7d2/0x1c10 security/integrity/ima/ima_main.c:260
> >
> > stack backtrace:
> > CPU: 1 PID: 3829 Comm: syz-executor450 Not tainted 5.19.0-rc4-syzkaller-00187-g089866061428 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
> > Call Trace:
> > <TASK>
> > __dump_stack lib/dump_stack.c:88 [inline]
> > dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
> > check_noncircular+0x2f7/0x3b0 kernel/locking/lockdep.c:2175
> > check_prev_add kernel/locking/lockdep.c:3095 [inline]
> > check_prevs_add kernel/locking/lockdep.c:3214 [inline]
> > validate_chain+0x185c/0x65c0 kernel/locking/lockdep.c:3829
> > __lock_acquire+0x129a/0x1f80 kernel/locking/lockdep.c:5053
> > lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5665
> > percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
> > __sb_start_write include/linux/fs.h:1699 [inline]
> > sb_start_write+0x4d/0x1a0 include/linux/fs.h:1774
> > mnt_want_write+0x3b/0x80 fs/namespace.c:393
> > ovl_maybe_copy_up+0x124/0x190 fs/overlayfs/copy_up.c:1078
> > ovl_open+0x106/0x2a0 fs/overlayfs/file.c:152
> > do_dentry_open+0x789/0x1040 fs/open.c:848
> > vfs_open fs/open.c:981 [inline]
> > dentry_open+0xc1/0x120 fs/open.c:997
> > ima_calc_file_hash+0x157/0x1cb0 security/integrity/ima/ima_crypto.c:557
> > ima_collect_measurement+0x3de/0x850 security/integrity/ima/ima_api.c:292
> > process_measurement+0xf87/0x1c10 security/integrity/ima/ima_main.c:337
> > ima_file_check+0xe7/0x160 security/integrity/ima/ima_main.c:517
> > do_open fs/namei.c:3522 [inline]
> > path_openat+0x2705/0x2ec0 fs/namei.c:3653
> > do_filp_open+0x277/0x4f0 fs/namei.c:3680
> > do_sys_openat2+0x13b/0x500 fs/open.c:1278
> > do_sys_open fs/open.c:1294 [inline]
> > __do_sys_open fs/open.c:1302 [inline]
> > __se_sys_open fs/open.c:1298 [inline]
> > __x64_sys_open+0x221/0x270 fs/open.c:1298
> > do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> > do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
> > entry_SYSCALL_64_after_hwframe+0x46/0xb0
> > RIP: 0033:0x7faf98402749
> > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 16 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007faf9838e2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> > RAX: ffffffffffffffda RBX: 00007faf98491270 RCX: 00007faf98402749
> > RDX: 0000000000000000 RSI: 000000000000000b RDI: 00000000200000c0
> > RBP: 00007faf98458504 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e
> > R13: 3d7269647265776f R14: 0079616c7265766f R15: 00007faf98491278
> > </TASK>
> >
--->8---
From: Hillf Danton <hdanton@sina.com>
Subject: [PATCH] integrity: lockdep annotate of iint->mutex
This fixes a reported lockdep splat
CPU0 CPU1
---- ----
lock(&iint->mutex);
lock(sb_writers#4);
lock(&iint->mutex);
lock(sb_writers#4);
*** DEADLOCK ***
using the method in 4eae06de482b annotating OVL_I(inode)->lock.
Links: https://lore.kernel.org/linux-unionfs/CAOQ4uxjk4XYuwz5HCmN-Ge=Ld=tM1f7ZxVrd5U1AC2Wisc9MTA@mail.gmail.com/
Reported-and-tested-by: syzbot <syzbot+b42fe626038981fb7bfa@syzkaller.appspotmail.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
---
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -85,6 +85,17 @@ static void iint_free(struct integrity_i
kmem_cache_free(iint_cache, iint);
}
+static void iint_annotate_mutex_key(struct integrity_iint_cache *iint, struct inode *inode)
+{
+#ifdef CONFIG_LOCKDEP
+ static struct lock_class_key iint_mutex_key[FILESYSTEM_MAX_STACK_DEPTH];
+
+ int depth = inode->i_sb->s_stack_depth;
+
+ lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]);
+#endif
+}
+
/**
* integrity_inode_get - find or allocate an iint associated with an inode
* @inode: pointer to the inode
@@ -114,6 +125,8 @@ struct integrity_iint_cache *integrity_i
if (!iint)
return NULL;
+ iint_annotate_mutex_key(iint, inode);
+
write_lock(&integrity_iint_lock);
p = &integrity_iint_tree.rb_node;
--
^ permalink raw reply [flat|nested] 2+ messages in thread