syzbot

audit: type=1804 audit(1656803882.106:2): pid=7971 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="open_writers" comm="syz-executor304" name="/root/bus/file0" dev="sda1" ino=13861 res=1
======================================================
WARNING: possible circular locking dependency detected
4.14.286-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor304/7971 is trying to acquire lock:
 (sb_writers#3){.+.+}, at: [<ffffffff818e059a>] sb_start_write include/linux/fs.h:1551 [inline]
 (sb_writers#3){.+.+}, at: [<ffffffff818e059a>] mnt_want_write+0x3a/0xb0 fs/namespace.c:386

but task is already holding lock:
 (&iint->mutex){+.+.}, at: [<ffffffff82eebf50>] process_measurement+0x270/0xb20 security/integrity/ima/ima_main.c:225

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&iint->mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       process_measurement+0x270/0xb20 security/integrity/ima/ima_main.c:225
       do_last fs/namei.c:3435 [inline]
       path_openat+0x10ad/0x2970 fs/namei.c:3569
       do_filp_open+0x179/0x3c0 fs/namei.c:3603
       do_sys_open+0x296/0x410 fs/open.c:1081
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

-> #0 (sb_writers#3){.+.+}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
       percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
       __sb_start_write+0x64/0x260 fs/super.c:1342
       sb_start_write include/linux/fs.h:1551 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:386
       ovl_open_maybe_copy_up+0xcf/0x130 fs/overlayfs/inode.c:344
       ovl_d_real+0xbc/0x350 fs/overlayfs/super.c:88
       d_real include/linux/dcache.h:587 [inline]
       vfs_open+0x19e/0x220 fs/open.c:882
       dentry_open+0xa7/0x210 fs/open.c:905
       ima_calc_file_hash+0x51c/0x780 security/integrity/ima/ima_crypto.c:452
       ima_collect_measurement+0x39d/0x430 security/integrity/ima/ima_api.c:227
       process_measurement+0x78b/0xb20 security/integrity/ima/ima_main.c:264
       do_last fs/namei.c:3435 [inline]
       path_openat+0x10ad/0x2970 fs/namei.c:3569
       do_filp_open+0x179/0x3c0 fs/namei.c:3603
       do_sys_open+0x296/0x410 fs/open.c:1081
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&iint->mutex);
                               lock(sb_writers#3);
                               lock(&iint->mutex);
  lock(sb_writers#3);

 *** DEADLOCK ***

1 lock held by syz-executor304/7971:
 #0:  (&iint->mutex){+.+.}, at: [<ffffffff82eebf50>] process_measurement+0x270/0xb20 security/integrity/ima/ima_main.c:225

stack backtrace:
CPU: 0 PID: 7971 Comm: syz-executor304 Not tainted 4.14.286-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
 percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
 __sb_start_write+0x64/0x260 fs/super.c:1342
 sb_start_write include/linux/fs.h:1551 [inline]
 mnt_want_write+0x3a/0xb0 fs/namespace.c:386
 ovl_open_maybe_copy_up+0xcf/0x130 fs/overlayfs/inode.c:344
 ovl_d_real+0xbc/0x350 fs/overlayfs/super.c:88
 d_real include/linux/dcache.h:587 [inline]
 vfs_open+0x19e/0x220 fs/open.c:882
 dentry_open+0xa7/0x210 fs/open.c:905
 ima_calc_file_hash+0x51c/0x780 security/integrity/ima/ima_crypto.c:452
 ima_collect_measurement+0x39d/0x430 security/integrity/ima/ima_api.c:227
 process_measurement+0x78b/0xb20 security/integrity/ima/ima_main.c:264
 do_last fs/namei.c:3435 [inline]
 path_openat+0x10ad/0x2970 fs/namei.c:3569
 do_filp_open+0x179/0x3c0 fs/namei.c:3603
 do_sys_open+0x296/0x410 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f829b7290c9
RSP: 002b:00007ffe5508e828 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f829b7290c9
RDX: 0000000000000000 RSI: 000000000000000b RDI: 00000000200000c0
RBP: 00007f829b6ed0b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000