====================================================== WARNING: possible circular locking dependency detected 5.1.0-rc6-next-20190426 #31 Not tainted ------------------------------------------------------ syz-executor.0/7790 is trying to acquire lock: 00000000b15a480c (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1621 [inline] 00000000b15a480c (sb_writers#3){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:358 but task is already holding lock: 00000000aed3dea4 (&iint->mutex){+.+.}, at: process_measurement+0x354/0x1570 security/integrity/ima/ima_main.c:226 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&iint->mutex){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4205 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 process_measurement+0x354/0x1570 security/integrity/ima/ima_main.c:226 ima_file_check+0xc5/0x110 security/integrity/ima/ima_main.c:393 do_last fs/namei.c:3420 [inline] path_openat+0x1142/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1069 __do_sys_open fs/open.c:1087 [inline] __se_sys_open fs/open.c:1082 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1082 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (sb_writers#3){.+.+}: check_prevs_add kernel/locking/lockdep.c:2325 [inline] validate_chain kernel/locking/lockdep.c:2706 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3695 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4205 percpu_down_read include/linux/percpu-rwsem.h:36 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1613 sb_start_write include/linux/fs.h:1621 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:358 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_open_maybe_copy_up+0x122/0x180 fs/overlayfs/copy_up.c:917 ovl_open+0xb3/0x270 fs/overlayfs/file.c:123 do_dentry_open+0x4e2/0x1250 fs/open.c:777 vfs_open fs/open.c:886 [inline] dentry_open+0x132/0x1d0 fs/open.c:902 ima_calc_file_hash+0x33f/0x570 security/integrity/ima/ima_crypto.c:426 ima_collect_measurement+0x50f/0x5c0 security/integrity/ima/ima_api.c:231 process_measurement+0xeca/0x1570 security/integrity/ima/ima_main.c:286 ima_file_check+0xc5/0x110 security/integrity/ima/ima_main.c:393 do_last fs/namei.c:3420 [inline] path_openat+0x1142/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1069 __do_sys_openat fs/open.c:1096 [inline] __se_sys_openat fs/open.c:1090 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1090 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe 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-executor.0/7790: #0: 00000000aed3dea4 (&iint->mutex){+.+.}, at: process_measurement+0x354/0x1570 security/integrity/ima/ima_main.c:226 stack backtrace: CPU: 0 PID: 7790 Comm: syz-executor.0 Not tainted 5.1.0-rc6-next-20190426 #31 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1560 check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2212 check_prevs_add kernel/locking/lockdep.c:2325 [inline] validate_chain kernel/locking/lockdep.c:2706 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3695 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4205 percpu_down_read include/linux/percpu-rwsem.h:36 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1613 sb_start_write include/linux/fs.h:1621 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:358 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_open_maybe_copy_up+0x122/0x180 fs/overlayfs/copy_up.c:917 ovl_open+0xb3/0x270 fs/overlayfs/file.c:123 do_dentry_open+0x4e2/0x1250 fs/open.c:777 vfs_open fs/open.c:886 [inline] dentry_open+0x132/0x1d0 fs/open.c:902 ima_calc_file_hash+0x33f/0x570 security/integrity/ima/ima_crypto.c:426 ima_collect_measurement+0x50f/0x5c0 security/integrity/ima/ima_api.c:231 process_measurement+0xeca/0x1570 security/integrity/ima/ima_main.c:286 ima_file_check+0xc5/0x110 security/integrity/ima/ima_main.c:393 do_last fs/namei.c:3420 [inline] path_openat+0x1142/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1069 __do_sys_openat fs/open.c:1096 [inline] __se_sys_openat fs/open.c:1090 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1090 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458da9 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffdd30c23c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458da9 RDX: 0000000000000003 RSI: 0000000020000200 RDI: ffffffffffffff9c RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00005555572a8914 R13: 00000000004c5098 R14: 00000000004d8f78 R15: 00000000ffffffff