audit: type=1400 audit(1567999580.324:8): avc: denied { map } for pid=1777 comm="syz-executor135" path="/dev/ashmem" dev="devtmpfs" ino=5461 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:device_t:s0 tclass=chr_file permissive=1 ====================================================== WARNING: possible circular locking dependency detected 4.14.142+ #0 Not tainted ------------------------------------------------------ syz-executor135/3291 is trying to acquire lock: (cpu_hotplug_lock.rw_sem){++++}, at: [< (ptrval)>] get_online_cpus include/linux/cpu.h:140 [inline] (cpu_hotplug_lock.rw_sem){++++}, at: [< (ptrval)>] lru_add_drain_all+0xa/0x20 mm/swap.c:729 but task is already holding lock: (&sb->s_type->i_mutex_key#10){+.+.}, at: [< (ptrval)>] inode_lock include/linux/fs.h:718 [inline] (&sb->s_type->i_mutex_key#10){+.+.}, at: [< (ptrval)>] shmem_add_seals+0x12b/0x11b0 mm/shmem.c:2829 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&sb->s_type->i_mutex_key#10){+.+.}: down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:718 [inline] shmem_fallocate+0x150/0xae0 mm/shmem.c:2902 ashmem_shrink_scan drivers/staging/android/ashmem.c:453 [inline] ashmem_shrink_scan+0x1ca/0x4f0 drivers/staging/android/ashmem.c:437 ashmem_ioctl+0x2b4/0xd20 drivers/staging/android/ashmem.c:795 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #4 (ashmem_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 ashmem_mmap+0x4c/0x450 drivers/staging/android/ashmem.c:369 call_mmap include/linux/fs.h:1793 [inline] mmap_region+0x7d9/0xfb0 mm/mmap.c:1732 do_mmap+0x548/0xb80 mm/mmap.c:1510 do_mmap_pgoff include/linux/mm.h:2209 [inline] vm_mmap_pgoff+0x177/0x1c0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1560 [inline] SyS_mmap_pgoff+0xf4/0x1b0 mm/mmap.c:1518 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #3 (&mm->mmap_sem){++++}: __might_fault mm/memory.c:4584 [inline] __might_fault+0x137/0x1b0 mm/memory.c:4569 _copy_from_user+0x27/0x100 lib/usercopy.c:10 copy_from_user include/linux/uaccess.h:147 [inline] perf_event_period kernel/events/core.c:4758 [inline] _perf_ioctl kernel/events/core.c:4816 [inline] perf_ioctl+0x431/0x1bb0 kernel/events/core.c:4883 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #2 (&cpuctx_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_init_cpu+0xa8/0x150 kernel/events/core.c:11231 perf_event_init+0x289/0x2c5 kernel/events/core.c:11278 start_kernel+0x583/0x890 init/main.c:645 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #1 (pmus_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_init_cpu+0x2c/0x150 kernel/events/core.c:11225 cpuhp_invoke_callback+0x207/0x1a30 kernel/cpu.c:184 cpuhp_up_callbacks kernel/cpu.c:572 [inline] _cpu_up+0x20b/0x500 kernel/cpu.c:1134 do_cpu_up+0x64/0x120 kernel/cpu.c:1169 smp_init+0x142/0x154 kernel/smp.c:578 kernel_init_freeable+0x196/0x3b0 init/main.c:1091 kernel_init+0xd/0x164 init/main.c:1023 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404 -> #0 (cpu_hotplug_lock.rw_sem){++++}: lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3991 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] cpus_read_lock+0x39/0xc0 kernel/cpu.c:295 get_online_cpus include/linux/cpu.h:140 [inline] lru_add_drain_all+0xa/0x20 mm/swap.c:729 shmem_wait_for_pins mm/shmem.c:2732 [inline] shmem_add_seals+0x633/0x11b0 mm/shmem.c:2841 shmem_fcntl+0xea/0x120 mm/shmem.c:2876 do_fcntl+0x5c8/0xd20 fs/fcntl.c:421 SYSC_fcntl fs/fcntl.c:463 [inline] SyS_fcntl+0xc6/0x100 fs/fcntl.c:448 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: cpu_hotplug_lock.rw_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#10); lock(ashmem_mutex); lock(&sb->s_type->i_mutex_key#10); lock(cpu_hotplug_lock.rw_sem); *** DEADLOCK *** 1 lock held by syz-executor135/3291: #0: (&sb->s_type->i_mutex_key#10){+.+.}, at: [< (ptrval)>] inode_lock include/linux/fs.h:718 [inline] #0: (&sb->s_type->i_mutex_key#10){+.+.}, at: [< (ptrval)>] shmem_add_seals+0x12b/0x11b0 mm/shmem.c:2829 stack backtrace: CPU: 1 PID: 3291 Comm: syz-executor135 Not tainted 4.14.142+ #0 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xca/0x134 lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2f5f/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3991 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] cpus_read_lock+0x39/0xc0 kernel/cpu.c:295 get_online_cpus include/linux/cpu.h:140 [inline] lru_add_drain_all+0xa/0x20 mm/swap.c:729 shmem_wait_for_pins mm/shmem.c:2732 [inline] shmem_add_seals+0x633/0x11b0 mm/shmem.c:2841 shmem_fcntl+0xea/0x120 mm/shmem.c:2876 do_fcntl+0x5c8/0xd20 fs/fcntl.c:421 SYSC_fcntl fs/fcntl.c:463 [inline] SyS_fcntl+0xc6/0x100 fs/fcntl.c:448 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4414a9 RSP: 002b:00007ffdbf069e78 EFLAGS: 00000246 ORIG_RAX: 0000000000000048 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004414a9 RDX: 0000000000000008 RSI: 0000000000000409 RDI: 0000000000000005 RBP: 0000000000005f60 R08: 00000000004002c8 R09: 00000000004002c8 R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000402220 R13: 00000000004022b0 R14: 0000000000000000 R15: 0000000000000000