[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 9.599981] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.726166] random: sshd: uninitialized urandom read (32 bytes read) [ 25.836856] random: crng init done Warning: Permanently added '10.128.0.157' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 43.497636] [ 43.499307] ====================================================== [ 43.505609] [ INFO: possible circular locking dependency detected ] [ 43.512002] 4.9.144+ #77 Not tainted [ 43.515698] ------------------------------------------------------- [ 43.522096] syz-executor286/2456 is trying to acquire lock: [ 43.527795] (&mm->mmap_sem){++++++}, at: [] __do_page_fault+0x7db/0xa60 [ 43.536642] but task is already holding lock: [ 43.541301] (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [] generic_file_write_iter+0x9d/0x620 [ 43.552068] which lock already depends on the new lock. [ 43.552068] [ 43.559070] [ 43.559070] the existing dependency chain (in reverse order) is: [ 43.566684] -> #2 (&sb->s_type->i_mutex_key#10){+.+.+.}: [ 43.572953] lock_acquire+0x130/0x3e0 [ 43.577274] down_write+0x41/0xa0 [ 43.581243] shmem_fallocate+0x13c/0xb10 [ 43.585822] ashmem_shrink_scan+0x1b9/0x4c0 [ 43.591177] ashmem_ioctl+0x2c3/0xf00 [ 43.595607] do_vfs_ioctl+0x1ac/0x11a0 [ 43.600029] SyS_ioctl+0x8f/0xc0 [ 43.603929] do_syscall_64+0x19f/0x550 [ 43.608367] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 43.613999] -> #1 (ashmem_mutex){+.+.+.}: [ 43.618927] lock_acquire+0x130/0x3e0 [ 43.623241] mutex_lock_nested+0xc0/0x900 [ 43.627929] ashmem_mmap+0x55/0x480 [ 43.632086] mmap_region+0x80c/0xf90 [ 43.636307] do_mmap+0x53d/0xbb0 [ 43.640189] vm_mmap_pgoff+0x168/0x1b0 [ 43.644601] SyS_mmap_pgoff+0xfe/0x1b0 [ 43.649006] SyS_mmap+0x16/0x20 [ 43.652802] do_syscall_64+0x19f/0x550 [ 43.657203] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 43.662817] -> #0 (&mm->mmap_sem){++++++}: [ 43.667763] __lock_acquire+0x3189/0x4a10 [ 43.672423] lock_acquire+0x130/0x3e0 [ 43.676740] down_read+0x44/0xb0 [ 43.680623] __do_page_fault+0x7db/0xa60 [ 43.685197] do_page_fault+0x27/0x30 [ 43.689437] page_fault+0x25/0x30 [ 43.693413] generic_perform_write+0x1c7/0x500 [ 43.698504] __generic_file_write_iter+0x352/0x540 [ 43.703953] generic_file_write_iter+0x37a/0x620 [ 43.709227] __vfs_write+0x3d7/0x580 [ 43.713452] vfs_write+0x187/0x520 [ 43.717598] SyS_write+0xd9/0x1c0 [ 43.721572] do_syscall_64+0x19f/0x550 [ 43.725985] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 43.731601] [ 43.731601] other info that might help us debug this: [ 43.731601] [ 43.739732] Chain exists of: &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10 [ 43.749597] Possible unsafe locking scenario: [ 43.749597] [ 43.755642] CPU0 CPU1 [ 43.760293] ---- ---- [ 43.764952] lock(&sb->s_type->i_mutex_key#10); [ 43.770090] lock(ashmem_mutex); [ 43.776316] lock(&sb->s_type->i_mutex_key#10); [ 43.784002] lock(&mm->mmap_sem); [ 43.787791] [ 43.787791] *** DEADLOCK *** [ 43.787791] [ 43.793840] 2 locks held by syz-executor286/2456: [ 43.798671] #0: (sb_writers#6){.+.+.+}, at: [] vfs_write+0x3eb/0x520 [ 43.807590] #1: (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [] generic_file_write_iter+0x9d/0x620 [ 43.818915] [ 43.818915] stack backtrace: [ 43.823411] CPU: 1 PID: 2456 Comm: syz-executor286 Not tainted 4.9.144+ #77 [ 43.830503] ffff8801ce02f548 ffffffff81b43b89 ffffffff83cc3270 ffffffff83cae600 [ 43.838561] ffffffff83ca4e20 ffff8801c55288f8 ffff8801c5528000 ffff8801ce02f590 [ 43.846633] ffffffff813ff290 0000000000000002 00000000c55288d8 0000000000000002 [ 43.854674] Call Trace: [ 43.857255] [] dump_stack+0xc1/0x128 [ 43.862615] [] print_circular_bug.cold.36+0x2f7/0x432 [ 43.869448] [] __lock_acquire+0x3189/0x4a10 [ 43.875415] [] ? get_page_from_freelist+0xda3/0x1d80 [ 43.882169] [] ? trace_hardirqs_on+0x10/0x10 [ 43.888227] [] ? check_preemption_disabled+0x3b/0x200 [ 43.895087] [] lock_acquire+0x130/0x3e0 [ 43.900709] [] ? __do_page_fault+0x7db/0xa60 [ 43.906761] [] down_read+0x44/0xb0 [ 43.911947] [] ? __do_page_fault+0x7db/0xa60 [ 43.918026] [] __do_page_fault+0x7db/0xa60 [ 43.923917] [] ? bad_area_access_error+0x3a0/0x3a0 [ 43.930491] [] ? debug_lockdep_rcu_enabled+0x77/0x90 [ 43.937239] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 43.943911] [] do_page_fault+0x27/0x30 [ 43.949446] [] page_fault+0x25/0x30 [ 43.954714] [] ? shmem_put_link+0xe0/0xe0 [ 43.960509] [] ? iov_iter_fault_in_readable+0x330/0x400 [ 43.967520] [] ? iov_iter_fault_in_readable+0x323/0x400 [ 43.974527] [] ? flex_array_free_parts+0xe0/0xe0 [ 43.980934] [] ? do_writepages+0x160/0x1d0 [ 43.986817] [] ? do_writepages+0x1d0/0x1d0 [ 43.992696] [] ? iov_iter_advance+0x216/0xd40 [ 43.998839] [] generic_perform_write+0x1c7/0x500 [ 44.005248] [] ? filemap_page_mkwrite+0x280/0x280 [ 44.011747] [] ? file_update_time+0xbc/0x390 [ 44.017813] [] ? current_time+0xd0/0xd0 [ 44.023463] [] __generic_file_write_iter+0x352/0x540 [ 44.030207] [] generic_file_write_iter+0x37a/0x620 [ 44.036779] [] __vfs_write+0x3d7/0x580 [ 44.042311] [] ? __vfs_read+0x560/0x560 [ 44.047937] [] ? rcu_sync_lockdep_assert+0x73/0xb0 [ 44.054528] [] ? __sb_start_write+0x161/0x300 [ 44.060664] [] vfs_write+0x187/0x520 [ 44.066026] [] SyS_write+0xd9/0x1c0 [ 44.071300] [] ? SyS_read+0x1c0/0x1c0 [ 44.076740] [] ? do_syscall_64+0x48/0x550 [ 44.082536] [] ? SyS_read+0x1c0/0x1c0 [ 44.087982] [] do_syscall_64+0x19f/0x550 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 44.093691] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program