audit: type=1400 audit(1593327244.921:8): avc:  denied  { execmem } for  pid=6456 comm="syz-executor152" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
======================================================
WARNING: possible circular locking dependency detected
4.19.130-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor152/6456 is trying to acquire lock:
00000000aff70836 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline]
00000000aff70836 (sb_writers#3){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360

but task is already holding lock:
00000000c96c2814 (&iint->mutex){+.+.}, at: process_measurement+0x316/0x1440 security/integrity/ima/ima_main.c:224

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&iint->mutex){+.+.}:
       process_measurement+0x316/0x1440 security/integrity/ima/ima_main.c:224
       ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:391
       do_last fs/namei.c:3425 [inline]
       path_openat+0x7e4/0x2df0 fs/namei.c:3537
       do_filp_open+0x18c/0x3f0 fs/namei.c:3567
       do_sys_open+0x3b3/0x520 fs/open.c:1085
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (sb_writers#3){.+.+}:
       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+0x1f3/0x350 fs/super.c:1387
       sb_start_write include/linux/fs.h:1579 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:360
       ovl_maybe_copy_up+0x11f/0x190 fs/overlayfs/copy_up.c:886
       ovl_open+0xb4/0x350 fs/overlayfs/file.c:124
       do_dentry_open+0x4aa/0x1160 fs/open.c:796
       vfs_open fs/open.c:902 [inline]
       dentry_open+0x132/0x1d0 fs/open.c:918
       ima_calc_file_hash+0x687/0x990 security/integrity/ima/ima_crypto.c:435
       ima_collect_measurement+0x4c4/0x570 security/integrity/ima/ima_api.c:231
       process_measurement+0xddd/0x1440 security/integrity/ima/ima_main.c:284
       ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:391
       do_last fs/namei.c:3425 [inline]
       path_openat+0x7e4/0x2df0 fs/namei.c:3537
       do_filp_open+0x18c/0x3f0 fs/namei.c:3567
       do_sys_open+0x3b3/0x520 fs/open.c:1085
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       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-executor152/6456:
 #0: 00000000c96c2814 (&iint->mutex){+.+.}, at: process_measurement+0x316/0x1440 security/integrity/ima/ima_main.c:224

stack backtrace:
CPU: 0 PID: 6456 Comm: syz-executor152 Not tainted 4.19.130-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+0x1fc/0x2fe lib/dump_stack.c:118
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1221
 check_prev_add kernel/locking/lockdep.c:1865 [inline]
 check_prevs_add kernel/locking/lockdep.c:1978 [inline]
 validate_chain kernel/locking/lockdep.c:2419 [inline]
 __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3415
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907
 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+0x1f3/0x350 fs/super.c:1387
 sb_start_write include/linux/fs.h:1579 [inline]
 mnt_want_write+0x3a/0xb0 fs/namespace.c:360
 ovl_maybe_copy_up+0x11f/0x190 fs/overlayfs/copy_up.c:886
 ovl_open+0xb4/0x350 fs/overlayfs/file.c:124
 do_dentry_open+0x4aa/0x1160 fs/open.c:796
 vfs_open fs/open.c:902 [inline]
 dentry_open+0x132/0x1d0 fs/open.c:918
 ima_calc_file_hash+0x687/0x990 security/integrity/ima/ima_crypto.c:435
 ima_collect_measurement+0x4c4/0x570 security/integrity/ima/ima_api.c:231
 process_measurement+0xddd/0x1440 security/integrity/ima/ima_main.c:284
 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:391
 do_last fs/namei.c:3425 [inline]
 path_openat+0x7e4/0x2df0 fs/namei.c:3537
 do_filp_open+0x18c/0x3f0 fs/namei.c:3567
 do_sys_open+0x3b3/0x520 fs/open.c:1085
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440399
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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