====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc4+ #348 Not tainted ------------------------------------------------------ syz-executor4/13234 is trying to acquire lock: (&sb->s_type->i_mutex_key#11){++++}, at: [<00000000458fd721>] inode_lock include/linux/fs.h:713 [inline] (&sb->s_type->i_mutex_key#11){++++}, at: [<00000000458fd721>] shmem_file_llseek+0xef/0x240 mm/shmem.c:2579 but task is already holding lock: (ashmem_mutex){+.+.}, at: [<0000000010373dc6>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:326 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+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 ashmem_mmap+0x53/0x410 drivers/staging/android/ashmem.c:362 call_mmap include/linux/fs.h:1786 [inline] mmap_region+0xa99/0x15a0 mm/mmap.c:1705 do_mmap+0x6c0/0xe00 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2223 [inline] vm_mmap_pgoff+0x1de/0x280 mm/util.c:355 SYSC_mmap_pgoff mm/mmap.c:1533 [inline] SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&mm->mmap_sem){++++}: __might_fault+0x13a/0x1d0 mm/memory.c:4571 _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] filldir+0x1a7/0x320 fs/readdir.c:196 dir_emit_dot include/linux/fs.h:3370 [inline] dir_emit_dots include/linux/fs.h:3381 [inline] dcache_readdir+0x12d/0x5e0 fs/libfs.c:192 iterate_dir+0x1ca/0x530 fs/readdir.c:51 SYSC_getdents fs/readdir.c:231 [inline] SyS_getdents+0x225/0x450 fs/readdir.c:212 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&sb->s_type->i_mutex_key#11){++++}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 down_write+0x87/0x120 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:713 [inline] shmem_file_llseek+0xef/0x240 mm/shmem.c:2579 vfs_llseek+0xa2/0xd0 fs/read_write.c:300 ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:338 vfs_llseek fs/read_write.c:300 [inline] SYSC_lseek fs/read_write.c:313 [inline] SyS_lseek+0xeb/0x170 fs/read_write.c:304 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 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-executor4/13234: #0: (ashmem_mutex){+.+.}, at: [<0000000010373dc6>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:326 stack backtrace: CPU: 0 PID: 13234 Comm: syz-executor4 Not tainted 4.16.0-rc4+ #348 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223 check_prev_add kernel/locking/lockdep.c:1863 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2417 [inline] __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 down_write+0x87/0x120 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:713 [inline] shmem_file_llseek+0xef/0x240 mm/shmem.c:2579 vfs_llseek+0xa2/0xd0 fs/read_write.c:300 ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:338 vfs_llseek fs/read_write.c:300 [inline] SYSC_lseek fs/read_write.c:313 [inline] SyS_lseek+0xeb/0x170 fs/read_write.c:304 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x453e69 RSP: 002b:00007f498bf7fc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000008 RAX: ffffffffffffffda RBX: 00007f498bf806d4 RCX: 0000000000453e69 RDX: 0000000000000003 RSI: 0000000000000003 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003da R14: 00000000006f5d10 R15: 0000000000000000 audit: type=1326 audit(1520713025.843:85): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13321 comm="syz-executor4" exe="/root/syz-executor4" sig=31 arch=c000003e syscall=202 compat=0 ip=0x453e69 code=0x0 binder_alloc: binder_alloc_mmap_handler: 13322 20000000-20002000 already mapped failed -16 audit: type=1326 audit(1520713025.873:86): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13321 comm="syz-executor4" exe="/root/syz-executor4" sig=31 arch=c000003e syscall=228 compat=0 ip=0x456c8a code=0x0 audit: type=1326 audit(1520713025.875:87): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=13321 comm="syz-executor4" exe="/root/syz-executor4" sig=31 arch=c000003e syscall=273 compat=0 ip=0x40b1b4 code=0x0 FAULT_INJECTION: forcing a failure. name fail_page_alloc, interval 1, probability 0, space 0, times 1 CPU: 0 PID: 13407 Comm: syz-executor7 Not tainted 4.16.0-rc4+ #348 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 fail_dump lib/fault-inject.c:51 [inline] should_fail+0x8c0/0xa40 lib/fault-inject.c:149 should_fail_alloc_page mm/page_alloc.c:2959 [inline] prepare_alloc_pages mm/page_alloc.c:4198 [inline] __alloc_pages_nodemask+0x327/0xdd0 mm/page_alloc.c:4237 alloc_pages_current+0xb6/0x1e0 mm/mempolicy.c:2055 alloc_pages include/linux/gfp.h:492 [inline] skb_page_frag_refill+0x358/0x5f0 net/core/sock.c:2208 tun_build_skb.isra.50+0x2f0/0x1840 drivers/net/tun.c:1626 tun_get_user+0x18fa/0x3810 drivers/net/tun.c:1803 tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1989 call_write_iter include/linux/fs.h:1781 [inline] do_iter_readv_writev+0x55c/0x830 fs/read_write.c:653 do_iter_write+0x154/0x540 fs/read_write.c:932 vfs_writev+0x18a/0x340 fs/read_write.c:977 do_writev+0xfc/0x2a0 fs/read_write.c:1012 SYSC_writev fs/read_write.c:1085 [inline] SyS_writev+0x27/0x30 fs/read_write.c:1082 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x453d41 RSP: 002b:00007ff3ff8e0ba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 0000000000000271 RCX: 0000000000453d41 RDX: 0000000000000001 RSI: 00007ff3ff8e0bf0 RDI: 00000000000000fc RBP: 0000000020000080 R08: 00000000000000fc R09: 0000000000000000 R10: 0000000000000271 R11: 0000000000000293 R12: 0000000000000013 R13: 0000000000000622 R14: 00000000006f93d0 R15: 0000000000000000 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 1 CPU: 1 PID: 14515 Comm: syz-executor0 Not tainted 4.16.0-rc4+ #348 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 fail_dump lib/fault-inject.c:51 [inline] should_fail+0x8c0/0xa40 lib/fault-inject.c:149 should_failslab+0xec/0x120 mm/failslab.c:32 slab_pre_alloc_hook mm/slab.h:422 [inline] slab_alloc mm/slab.c:3365 [inline] kmem_cache_alloc_trace+0x4b/0x740 mm/slab.c:3605 kmalloc include/linux/slab.h:512 [inline] kzalloc include/linux/slab.h:701 [inline] kvm_create_pit+0xc2/0x860 arch/x86/kvm/i8254.c:656 kvm_arch_vm_ioctl+0x13b7/0x2130 arch/x86/kvm/x86.c:4278 kvm_vm_ioctl+0x238/0x1cf0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3100 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x453e69 RSP: 002b:00007fabb8a14c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fabb8a156d4 RCX: 0000000000453e69 RDX: 0000000020516000 RSI: 000000004040ae77 RDI: 0000000000000014 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015 R13: 000000000000021c R14: 00000000006f3340 R15: 0000000000000000 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 1 PID: 14563 Comm: syz-executor4 Not tainted 4.16.0-rc4+ #348 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 fail_dump lib/fault-inject.c:51 [inline] should_fail+0x8c0/0xa40 lib/fault-inject.c:149 should_failslab+0xec/0x120 mm/failslab.c:32 slab_pre_alloc_hook mm/slab.h:422 [inline] slab_alloc mm/slab.c:3365 [inline] kmem_cache_alloc_trace+0x4b/0x740 mm/slab.c:3605 kmalloc include/linux/slab.h:512 [inline] kzalloc include/linux/slab.h:701 [inline] kvm_pic_init+0x51/0x360 arch/x86/kvm/i8259.c:586 kvm_arch_vm_ioctl+0x1543/0x2130 arch/x86/kvm/x86.c:4241 kvm_vm_ioctl+0x238/0x1cf0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3100 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x453e69 RSP: 002b:00007f498bf7fc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f498bf806d4 RCX: 0000000000453e69 RDX: 0000000000000000 RSI: 000000000000ae60 RDI: 0000000000000014 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015 R13: 000000000000021b R14: 00000000006f3328 R15: 0000000000000000