====================================================== [ INFO: possible circular locking dependency detected ] 4.9.141+ #23 Not tainted ------------------------------------------------------- syz-executor.4/1838 is trying to acquire lock: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 but task is already holding lock: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [] lo_compat_ioctl+0x103/0x140 drivers/block/loop.c:1555 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 __mutex_lock_common kernel/locking/mutex.c:521 [inline] mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621 __lo_release drivers/block/loop.c:1609 [inline] lo_release+0x85/0x1a0 drivers/block/loop.c:1632 __blkdev_put+0x636/0x840 fs/block_dev.c:1598 blkdev_put+0x85/0x560 fs/block_dev.c:1663 blkdev_close+0x8b/0xb0 fs/block_dev.c:1670 __fput+0x263/0x700 fs/file_table.c:208 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x10c/0x180 kernel/task_work.c:116 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x129/0x150 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] do_syscall_64+0x3e2/0x550 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_swapgs+0x5d/0xdb lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 __mutex_lock_common kernel/locking/mutex.c:521 [inline] mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621 lo_open+0x1b/0xa0 drivers/block/loop.c:1589 __blkdev_get+0x263/0xd60 fs/block_dev.c:1282 blkdev_get+0x2da/0x920 fs/block_dev.c:1416 blkdev_open+0x1a5/0x250 fs/block_dev.c:1571 do_dentry_open+0x3ef/0xc90 fs/open.c:766 vfs_open+0x11c/0x210 fs/open.c:879 do_last fs/namei.c:3410 [inline] path_openat+0x542/0x2790 fs/namei.c:3534 do_filp_open+0x197/0x270 fs/namei.c:3568 do_sys_open+0x30d/0x5c0 fs/open.c:1072 SYSC_open fs/open.c:1090 [inline] SyS_open+0x2d/0x40 fs/open.c:1085 do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb check_prev_add kernel/locking/lockdep.c:1828 [inline] check_prevs_add kernel/locking/lockdep.c:1938 [inline] validate_chain kernel/locking/lockdep.c:2265 [inline] __lock_acquire+0x3189/0x4a10 kernel/locking/lockdep.c:3345 lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 __mutex_lock_common kernel/locking/mutex.c:521 [inline] mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621 blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:637 loop_set_status+0xa7e/0xfe0 drivers/block/loop.c:1181 loop_set_status_compat+0x9a/0xf0 drivers/block/loop.c:1528 lo_compat_ioctl+0x10e/0x140 drivers/block/loop.c:1556 compat_blkdev_ioctl+0x3a4/0x3630 block/compat_ioctl.c:751 C_SYSC_ioctl fs/compat_ioctl.c:1602 [inline] compat_SyS_ioctl+0x12d/0x1fd0 fs/compat_ioctl.c:1549 do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 other info that might help us debug this: Chain exists of: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&lo->lo_ctl_mutex#2); lock(loop_index_mutex); lock(&lo->lo_ctl_mutex#2); lock(&bdev->bd_mutex); *** DEADLOCK *** 1 lock held by syz-executor.4/1838: #0: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [] lo_compat_ioctl+0x103/0x140 drivers/block/loop.c:1555 stack backtrace: CPU: 1 PID: 1838 Comm: syz-executor.4 Not tainted 4.9.141+ #23 ffff8801d2b1f788 ffffffff81b42e79 ffffffff83c8e1b0 ffffffff83cb3c20 ffffffff83c8d430 ffff8801d38f08d0 ffff8801d38f0000 ffff8801d2b1f7d0 ffffffff813fee40 0000000000000001 00000000d38f08b0 0000000000000001 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_circular_bug.cold.36+0x2f7/0x432 kernel/locking/lockdep.c:1202 [] check_prev_add kernel/locking/lockdep.c:1828 [inline] [] check_prevs_add kernel/locking/lockdep.c:1938 [inline] [] validate_chain kernel/locking/lockdep.c:2265 [inline] [] __lock_acquire+0x3189/0x4a10 kernel/locking/lockdep.c:3345 [] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621 [] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 [] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:637 [] loop_set_status+0xa7e/0xfe0 drivers/block/loop.c:1181 [] loop_set_status_compat+0x9a/0xf0 drivers/block/loop.c:1528 [] lo_compat_ioctl+0x10e/0x140 drivers/block/loop.c:1556 [] compat_blkdev_ioctl+0x3a4/0x3630 block/compat_ioctl.c:751 [] C_SYSC_ioctl fs/compat_ioctl.c:1602 [inline] [] compat_SyS_ioctl+0x12d/0x1fd0 fs/compat_ioctl.c:1549 [] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] [] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 [] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 loop_reread_partitions: partition scan of loop0 ('Ԫd܎Et*sg8U`_%Z(r.yo-cB~k~KbwЋeC!qT) failed (rc=-13) audit_printk_skb: 1935 callbacks suppressed audit: type=1400 audit(1575400814.213:159710): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.213:159711): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.213:159712): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.213:159713): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.213:159714): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.213:159715): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.223:159716): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.223:159717): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.223:159718): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400814.223:159719): avc: denied { net_admin } for pid=2080 comm="syz-executor.2" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 device lo entered promiscuous mode device lo left promiscuous mode device lo entered promiscuous mode device lo left promiscuous mode device lo entered promiscuous mode device lo left promiscuous mode device lo entered promiscuous mode device lo left promiscuous mode audit_printk_skb: 4166 callbacks suppressed audit: type=1400 audit(1575400819.253:161111): avc: denied { sys_admin } for pid=2078 comm="syz-executor.3" capability=21 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.293:161112): avc: denied { dac_override } for pid=2102 comm="syz-executor.2" capability=1 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.303:161113): avc: denied { sys_admin } for pid=2080 comm="syz-executor.2" capability=21 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.303:161114): avc: denied { sys_admin } for pid=2080 comm="syz-executor.2" capability=21 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.313:161115): avc: denied { sys_admin } for pid=2080 comm="syz-executor.2" capability=21 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.313:161116): avc: denied { net_raw } for pid=2105 comm="syz-executor.1" capability=13 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.343:161118): avc: denied { net_admin } for pid=2101 comm="syz-executor.0" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.313:161117): avc: denied { sys_admin } for pid=2080 comm="syz-executor.2" capability=21 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.343:161119): avc: denied { net_admin } for pid=2101 comm="syz-executor.0" capability=12 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 audit: type=1400 audit(1575400819.353:161120): avc: denied { dac_override } for pid=2103 comm="syz-executor.4" capability=1 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 ip6_tunnel: xmit: Local address not yet configured!