random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) ====================================================== WARNING: possible circular locking dependency detected 4.14.67+ #1 Not tainted ------------------------------------------------------ syz-executor947/1975 is trying to acquire lock: (&sb->s_type->i_mutex_key#11){++++}, at: [] inode_lock include/linux/fs.h:713 [inline] (&sb->s_type->i_mutex_key#11){++++}, at: [] shmem_fallocate+0x149/0xb20 mm/shmem.c:2850 but task is already holding lock: (ashmem_mutex){+.+.}, at: [] ashmem_shrink_scan+0x52/0x4e0 drivers/staging/android/ashmem.c:440 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (ashmem_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893 ashmem_mmap+0x4c/0x3b0 drivers/staging/android/ashmem.c:369 call_mmap include/linux/fs.h:1787 [inline] mmap_region+0x836/0xfb0 mm/mmap.c:1731 do_mmap+0x551/0xb80 mm/mmap.c:1509 do_mmap_pgoff include/linux/mm.h:2167 [inline] vm_mmap_pgoff+0x180/0x1d0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1559 [inline] SyS_mmap_pgoff+0xf8/0x1a0 mm/mmap.c:1517 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&mm->mmap_sem){++++}: __might_fault+0x137/0x1b0 mm/memory.c:4519 _copy_to_user+0x27/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] filldir+0x192/0x340 fs/readdir.c:197 dir_emit_dot include/linux/fs.h:3380 [inline] dir_emit_dots include/linux/fs.h:3391 [inline] dcache_readdir+0x12f/0x5d0 fs/libfs.c:192 iterate_dir+0x19f/0x5e0 fs/readdir.c:52 SYSC_getdents fs/readdir.c:232 [inline] SyS_getdents+0x146/0x270 fs/readdir.c:213 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&sb->s_type->i_mutex_key#11){++++}: lock_acquire+0x10f/0x380 kernel/locking/lockdep.c:3991 down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:713 [inline] shmem_fallocate+0x149/0xb20 mm/shmem.c:2850 ashmem_shrink_scan+0x1b6/0x4e0 drivers/staging/android/ashmem.c:447 ashmem_ioctl+0x2cc/0xe20 drivers/staging/android/ashmem.c:789 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1a0/0x1030 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7e/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#11 --> &mm->mmap_sem --> ashmem_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ashmem_mutex); lock(&mm->mmap_sem); lock(ashmem_mutex); lock(&sb->s_type->i_mutex_key#11); *** DEADLOCK *** 1 lock held by syz-executor947/1975: #0: (ashmem_mutex){+.+.}, at: [] ashmem_shrink_scan+0x52/0x4e0 drivers/staging/android/ashmem.c:440 stack backtrace: CPU: 0 PID: 1975 Comm: syz-executor947 Not tainted 4.14.67+ #1 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x11b lib/dump_stack.c:53 print_circular_bug.isra.18.cold.43+0x2d3/0x40c 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+0x2ff9/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x10f/0x380 kernel/locking/lockdep.c:3991 down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:713 [inline] shmem_fallocate+0x149/0xb20 mm/shmem.c:2850 ashmem_shrink_scan+0x1b6/0x4e0 drivers/staging/android/ashmem.c:447 ashmem_ioctl+0x2cc/0xe20 drivers/staging/android/ashmem.c:789 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1a0/0x1030 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7e/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0