====================================================== WARNING: possible circular locking dependency detected 5.9.0-rc3-next-20200903-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.2/9443 is trying to acquire lock: ffff8880a707caa0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x363/0x1760 security/integrity/ima/ima_main.c:247 but task is already holding lock: ffff888214ae4460 (sb_writers#4){.+.+}-{0:0}, at: sb_start_write include/linux/fs.h:1653 [inline] ffff888214ae4460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:354 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sb_writers#4){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write+0x234/0x470 fs/super.c:1672 sb_start_write include/linux/fs.h:1653 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:354 ovl_maybe_copy_up+0x11f/0x190 fs/overlayfs/copy_up.c:990 ovl_open+0xba/0x270 fs/overlayfs/file.c:147 do_dentry_open+0x4b9/0x11b0 fs/open.c:817 vfs_open fs/open.c:931 [inline] dentry_open+0x132/0x1d0 fs/open.c:947 ima_calc_file_hash+0x32b/0x570 security/integrity/ima/ima_crypto.c:557 ima_collect_measurement+0x4ca/0x570 security/integrity/ima/ima_api.c:250 process_measurement+0xca6/0x1760 security/integrity/ima/ima_main.c:324 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:492 do_open fs/namei.c:3253 [inline] path_openat+0x154d/0x2730 fs/namei.c:3368 do_filp_open+0x17e/0x3c0 fs/namei.c:3395 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_open fs/open.c:1192 [inline] __se_sys_open fs/open.c:1188 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1188 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&iint->mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x29bb/0x5570 kernel/locking/lockdep.c:4426 lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x134/0x10e0 kernel/locking/mutex.c:1103 process_measurement+0x363/0x1760 security/integrity/ima/ima_main.c:247 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:492 do_open fs/namei.c:3253 [inline] path_openat+0x154d/0x2730 fs/namei.c:3368 do_filp_open+0x17e/0x3c0 fs/namei.c:3395 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1195 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#4); lock(&iint->mutex); lock(sb_writers#4); lock(&iint->mutex); *** DEADLOCK *** 1 lock held by syz-executor.2/9443: #0: ffff888214ae4460 (sb_writers#4){.+.+}-{0:0}, at: sb_start_write include/linux/fs.h:1653 [inline] #0: ffff888214ae4460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:354 stack backtrace: CPU: 0 PID: 9443 Comm: syz-executor.2 Not tainted 5.9.0-rc3-next-20200903-syzkaller #0 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+0x198/0x1fd lib/dump_stack.c:118 check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827 check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x29bb/0x5570 kernel/locking/lockdep.c:4426 lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x134/0x10e0 kernel/locking/mutex.c:1103 process_measurement+0x363/0x1760 security/integrity/ima/ima_main.c:247 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:492 do_open fs/namei.c:3253 [inline] path_openat+0x154d/0x2730 fs/namei.c:3368 do_filp_open+0x17e/0x3c0 fs/namei.c:3395 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1195 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fee38150c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000000223c0 RCX: 000000000045d5b9 RDX: 000000000000275a RSI: 0000000020000280 RDI: ffffffffffffff9c RBP: 000000000118cf88 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe8f9846ef R14: 00007fee381519c0 R15: 000000000118cf4c