[ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.236' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 92.601264][ T37] audit: type=1400 audit(1622582391.710:8): avc: denied { execmem } for pid=8455 comm="syz-executor968" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1 [ 92.606024][ T8455] [ 92.624405][ T8455] ====================================================== [ 92.631506][ T8455] WARNING: possible circular locking dependency detected [ 92.638510][ T8455] 5.13.0-rc4-syzkaller #0 Not tainted [ 92.643860][ T8455] ------------------------------------------------------ [ 92.650854][ T8455] syz-executor968/8455 is trying to acquire lock: [ 92.657431][ T8455] ffff88801b5810e0 (&bdev->bd_mutex){+.+.}-{3:3}, at: del_gendisk+0x24b/0xa00 [ 92.666307][ T8455] [ 92.666307][ T8455] but task is already holding lock: [ 92.673738][ T8455] ffffffff8ca6c348 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_control_ioctl+0x7b/0x4f0 [ 92.683027][ T8455] [ 92.683027][ T8455] which lock already depends on the new lock. [ 92.683027][ T8455] [ 92.693407][ T8455] [ 92.693407][ T8455] the existing dependency chain (in reverse order) is: [ 92.702399][ T8455] [ 92.702399][ T8455] -> #1 (loop_ctl_mutex){+.+.}-{3:3}: [ 92.709956][ T8455] __mutex_lock+0x139/0x10c0 [ 92.715085][ T8455] lo_open+0x1a/0x130 [ 92.719578][ T8455] __blkdev_get+0x182/0xa30 [ 92.724591][ T8455] blkdev_get_by_dev+0x200/0x660 [ 92.730111][ T8455] blkdev_open+0x154/0x2b0 [ 92.735050][ T8455] do_dentry_open+0x4b9/0x11b0 [ 92.740324][ T8455] path_openat+0x1c0e/0x27e0 [ 92.745421][ T8455] do_filp_open+0x190/0x3d0 [ 92.750517][ T8455] do_sys_openat2+0x16d/0x420 [ 92.755702][ T8455] __x64_sys_open+0x119/0x1c0 [ 92.761841][ T8455] do_syscall_64+0x3a/0xb0 [ 92.766767][ T8455] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 92.773344][ T8455] [ 92.773344][ T8455] -> #0 (&bdev->bd_mutex){+.+.}-{3:3}: [ 92.780982][ T8455] __lock_acquire+0x2a17/0x5230 [ 92.786368][ T8455] lock_acquire+0x1ab/0x740 [ 92.791380][ T8455] __mutex_lock+0x139/0x10c0 [ 92.796479][ T8455] del_gendisk+0x24b/0xa00 [ 92.801399][ T8455] loop_control_ioctl+0x40d/0x4f0 [ 92.806932][ T8455] __x64_sys_ioctl+0x193/0x200 [ 92.812202][ T8455] do_syscall_64+0x3a/0xb0 [ 92.817125][ T8455] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 92.823524][ T8455] [ 92.823524][ T8455] other info that might help us debug this: [ 92.823524][ T8455] [ 92.833731][ T8455] Possible unsafe locking scenario: [ 92.833731][ T8455] [ 92.841169][ T8455] CPU0 CPU1 [ 92.846515][ T8455] ---- ---- [ 92.851893][ T8455] lock(loop_ctl_mutex); [ 92.856248][ T8455] lock(&bdev->bd_mutex); [ 92.863198][ T8455] lock(loop_ctl_mutex); [ 92.870048][ T8455] lock(&bdev->bd_mutex); [ 92.874469][ T8455] [ 92.874469][ T8455] *** DEADLOCK *** [ 92.874469][ T8455] [ 92.882623][ T8455] 1 lock held by syz-executor968/8455: [ 92.888072][ T8455] #0: ffffffff8ca6c348 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_control_ioctl+0x7b/0x4f0 [ 92.898084][ T8455] [ 92.898084][ T8455] stack backtrace: [ 92.903958][ T8455] CPU: 1 PID: 8455 Comm: syz-executor968 Not tainted 5.13.0-rc4-syzkaller #0 [ 92.912699][ T8455] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 92.922735][ T8455] Call Trace: [ 92.926090][ T8455] dump_stack+0x141/0x1d7 [ 92.930499][ T8455] check_noncircular+0x25f/0x2e0 [ 92.936406][ T8455] ? kasan_save_stack+0x32/0x40 [ 92.941245][ T8455] ? print_circular_bug+0x1e0/0x1e0 [ 92.946606][ T8455] ? __kasan_slab_free+0xcd/0x100 [ 92.951618][ T8455] ? kernfs_put.part.0+0x2c4/0x540 [ 92.956739][ T8455] ? kernfs_put+0x42/0x50 [ 92.961243][ T8455] ? __kernfs_remove+0x703/0xa90 [ 92.966255][ T8455] ? kernfs_remove_by_name_ns+0x51/0xb0 [ 92.972758][ T8455] ? sysfs_remove_files+0x87/0xf0 [ 92.977770][ T8455] ? lockdep_lock+0xc6/0x200 [ 92.982349][ T8455] ? call_rcu_zapped+0xb0/0xb0 [ 92.987362][ T8455] ? find_held_lock+0x2d/0x110 [ 92.992199][ T8455] __lock_acquire+0x2a17/0x5230 [ 92.997056][ T8455] ? lockdep_hardirqs_on_prepare+0x400/0x400 [ 93.003024][ T8455] lock_acquire+0x1ab/0x740 [ 93.007515][ T8455] ? del_gendisk+0x24b/0xa00 [ 93.012092][ T8455] ? lock_release+0x720/0x720 [ 93.016758][ T8455] ? find_held_lock+0x2d/0x110 [ 93.021507][ T8455] __mutex_lock+0x139/0x10c0 [ 93.026101][ T8455] ? del_gendisk+0x24b/0xa00 [ 93.030958][ T8455] ? mutex_lock_io_nested+0xf20/0xf20 [ 93.036320][ T8455] ? del_gendisk+0x24b/0xa00 [ 93.041028][ T8455] ? __mutex_unlock_slowpath+0xe2/0x610 [ 93.046651][ T8455] ? mutex_lock_io_nested+0xf20/0xf20 [ 93.052011][ T8455] ? wait_for_completion_io+0x270/0x270 [ 93.057563][ T8455] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70 [ 93.063880][ T8455] ? kernfs_remove_by_name_ns+0x62/0xb0 [ 93.069433][ T8455] ? sysfs_remove_files+0x87/0xf0 [ 93.074443][ T8455] del_gendisk+0x24b/0xa00 [ 93.078842][ T8455] loop_control_ioctl+0x40d/0x4f0 [ 93.083855][ T8455] ? loop_lookup+0x1d0/0x1d0 [ 93.088435][ T8455] ? security_file_ioctl+0x5c/0xb0 [ 93.093546][ T8455] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70 [ 93.099774][ T8455] ? loop_lookup+0x1d0/0x1d0 [ 93.104358][ T8455] __x64_sys_ioctl+0x193/0x200 [ 93.109109][ T8455] do_syscall_64+0x3a/0xb0 [ 93.113528][ T8455] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 93.119406][ T8455] RIP: 0033:0x43ee69 [ 93.123464][ T8455] Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 [ 93.143063][ T8455] RSP: 002b:00007ffd52554fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 93.151567][ T8455] RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ee69 [ 93.159715][ T8455] RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000004 [ 93.167697][ T8455] RBP: 0000000000402e50 R08: 0000000000400488 R09: 0000000000400488 [ 93.175738][ T8455] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402ee0 [ 93.183692][ T8455] R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488