====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc4+ #350 Not tainted ------------------------------------------------------ syz-executor4/28523 is trying to acquire lock: (&sb->s_type->i_mutex_key#11){++++}, at: [<000000002fa31716>] inode_lock include/linux/fs.h:713 [inline] (&sb->s_type->i_mutex_key#11){++++}, at: [<000000002fa31716>] shmem_file_llseek+0xef/0x240 mm/shmem.c:2579 but task is already holding lock: (ashmem_mutex){+.+.}, at: [<0000000005cdf96a>] 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-executor4/28523: #0: (ashmem_mutex){+.+.}, at: [<0000000005cdf96a>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:326 stack backtrace: CPU: 1 PID: 28523 Comm: syz-executor4 Not tainted 4.16.0-rc4+ #350 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:00007f513f695c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000008 RAX: ffffffffffffffda RBX: 00007f513f6966d4 RCX: 0000000000453e69 RDX: 0000000000000004 RSI: 000000000000000c RDI: 0000000000000014 RBP: 000000000072bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003da R14: 00000000006f5d10 R15: 0000000000000001 kauditd_printk_skb: 4 callbacks suppressed audit: type=1400 audit(1520824130.500:318): avc: denied { write } for pid=28530 comm="syz-executor2" name="map_files" dev="proc" ino=85466 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=dir permissive=1 audit: type=1400 audit(1520824130.532:319): avc: denied { setattr } for pid=28530 comm="syz-executor2" name="map_files" dev="proc" ino=85466 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=dir permissive=1 bond0 (unregistering): Released all slaves audit: type=1400 audit(1520824130.776:320): avc: denied { ipc_lock } for pid=28560 comm="syz-executor7" capability=14 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 rpcbind: RPC call returned error 22 binder: 28607:28616 BC_REQUEST_DEATH_NOTIFICATION invalid ref 0 binder: 28607:28616 unknown command 397867821 binder: 28607:28616 ioctl c0306201 20008fd0 returned -22 binder: 28607:28626 BC_REQUEST_DEATH_NOTIFICATION invalid ref 0 binder: 28607:28626 unknown command 397867821 binder: 28607:28626 ioctl c0306201 20008fd0 returned -22 audit: type=1400 audit(1520824131.120:321): avc: denied { net_broadcast } for pid=28630 comm="syz-executor3" capability=11 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 WARNING: CPU: 0 PID: 6168 at net/ipv6/xfrm6_tunnel.c:345 xfrm6_tunnel_net_exit+0x253/0x460 net/ipv6/xfrm6_tunnel.c:345 audit: type=1400 audit(1520824131.272:322): avc: denied { map } for pid=28624 comm="syz-executor5" path="/dev/usbmon0" dev="devtmpfs" ino=120 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:usbmon_device_t:s0 tclass=chr_file permissive=1