======================================================
[ INFO: possible circular locking dependency detected ]
4.4.120-gd63fdf6 #28 Not tainted
-------------------------------------------------------
syz-executor1/6511 is trying to acquire lock:
 (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<ffffffff81463361>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816

but task is already holding lock:
audit: type=1400 audit(1521940818.352:15): avc:  denied  { write } for  pid=6518 comm="syz-executor5" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1
SELinux:  unknown mount option
 (ashmem_mutex){+.+.+.}, at: [<ffffffff82c62016>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff8376a39b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8376a39b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
       [<ffffffff82c61463>] ashmem_mmap+0x53/0x400 drivers/staging/android/ashmem.c:366
       [<ffffffff814b0e4f>] mmap_region+0x94f/0x1250 mm/mmap.c:1664
       [<ffffffff814b1c4d>] do_mmap+0x4fd/0x9d0 mm/mmap.c:1441
       [<ffffffff814700ce>] do_mmap_pgoff include/linux/mm.h:1915 [inline]
       [<ffffffff814700ce>] vm_mmap_pgoff+0x16e/0x1c0 mm/util.c:296
       [<ffffffff814afe1f>] SYSC_mmap_pgoff mm/mmap.c:1491 [inline]
       [<ffffffff814afe1f>] SyS_mmap_pgoff+0x33f/0x560 mm/mmap.c:1449
       [<ffffffff8101beb6>] SYSC_mmap arch/x86/kernel/sys_x86_64.c:95 [inline]
       [<ffffffff8101beb6>] SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:86
       [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98

       [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff814956ea>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
       [<ffffffff8155ab22>] copy_to_user arch/x86/include/asm/uaccess.h:760 [inline]
       [<ffffffff8155ab22>] filldir+0x162/0x2d0 fs/readdir.c:180
       [<ffffffff8159820e>] dir_emit_dot include/linux/fs.h:3070 [inline]
       [<ffffffff8159820e>] dir_emit_dots include/linux/fs.h:3081 [inline]
       [<ffffffff8159820e>] dcache_readdir+0x11e/0x7b0 fs/libfs.c:150
       [<ffffffff8155a768>] iterate_dir+0x1c8/0x420 fs/readdir.c:42
       [<ffffffff8155b45a>] SYSC_getdents fs/readdir.c:215 [inline]
       [<ffffffff8155b45a>] SyS_getdents+0x14a/0x270 fs/readdir.c:196
       [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98

       [<ffffffff8123ab2f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff8123ab2f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff8123ab2f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff8123ab2f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
       [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff8376a39b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8376a39b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
       [<ffffffff81463361>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
       [<ffffffff8151c762>] vfs_llseek+0xa2/0xd0 fs/read_write.c:260
       [<ffffffff82c620a7>] ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:342
       [<ffffffff8151e56b>] vfs_llseek fs/read_write.c:260 [inline]
       [<ffffffff8151e56b>] SYSC_lseek fs/read_write.c:285 [inline]
       [<ffffffff8151e56b>] SyS_lseek+0xeb/0x170 fs/read_write.c:276
       [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98

other info that might help us debug this:

Chain exists of:
 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(ashmem_mutex);
                               lock(&mm->mmap_sem);
                               lock(ashmem_mutex);
  lock(&sb->s_type->i_mutex_key#10);

 *** DEADLOCK ***

1 lock held by syz-executor1/6511:
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c62016>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330

stack backtrace:
CPU: 1 PID: 6511 Comm: syz-executor1 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 07dba8e2b69be64f ffff8800ba11fad8 ffffffff81d0408d
 ffffffff851a0010 ffffffff851a9b50 ffffffff851be7c0 ffff8800b9f288f8
 ffff8800b9f28000 ffff8800ba11fb20 ffffffff81233ba1 ffff8800b9f288f8
Call Trace:
 [<ffffffff81d0408d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0408d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81233ba1>] print_circular_bug+0x271/0x310 kernel/locking/lockdep.c:1226
 [<ffffffff8123ab2f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff8123ab2f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff8123ab2f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff8123ab2f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
 [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
 [<ffffffff8376a39b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff8376a39b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
 [<ffffffff81463361>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
 [<ffffffff8151c762>] vfs_llseek+0xa2/0xd0 fs/read_write.c:260
 [<ffffffff82c620a7>] ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:342
 [<ffffffff8151e56b>] vfs_llseek fs/read_write.c:260 [inline]
 [<ffffffff8151e56b>] SYSC_lseek fs/read_write.c:285 [inline]
 [<ffffffff8151e56b>] SyS_lseek+0xeb/0x170 fs/read_write.c:276
 [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
IPVS: Creating netns size=2552 id=9
sd 0:0:1:0: [sg0] tag#2 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK
sd 0:0:1:0: [sg0] tag#2 CDB: Test Unit Ready
sd 0:0:1:0: [sg0] tag#2 CDB[00]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[10]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[20]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[30]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[40]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[50]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[60]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[70]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[80]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
sd 0:0:1:0: [sg0] tag#2 CDB[90]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[a0]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[b0]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[c0]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[d0]: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
sd 0:0:1:0: [sg0] tag#2 CDB[e0]: 00 00 00 00 00
binder: 7061:7067 unknown command 16474912
binder: 7061:7067 ioctl c0306201 20000000 returned -22
binder: 7061:7063 unknown command 16474912
binder: 7061:7063 ioctl c0306201 20000000 returned -22
binder: 7455:7461 ioctl c0306201 20008000 returned -14
binder_alloc: binder_alloc_mmap_handler: 7455 20000000-20002000 already mapped failed -16
binder: 7455:7461 ioctl c0306201 20008000 returned -14
binder: 7557:7558 tried to acquire reference to desc 0, got 1 instead
binder: BINDER_SET_CONTEXT_MGR already set
binder: 7557:7558 ioctl 40046207 0 returned -16
binder: BINDER_SET_CONTEXT_MGR already set
binder: 7557:7571 IncRefs 0 refcount change on invalid ref 1 ret -22
binder: 7557:7558 ioctl 40046207 0 returned -16
binder: 7626:7628 transaction failed 29189/-22, size 582-0 line 3005
binder: 7626:7642 transaction failed 29189/-22, size 582-0 line 3005
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
Option '                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     [   55.077476] netlink: 20 bytes leftover after parsing attributes in process `syz-executor4'.
netlink: 20 bytes leftover after parsing attributes in process `syz-executor4'.
audit_printk_skb: 12 callbacks suppressed
audit: type=1400 audit(1521940824.082:20): avc:  denied  { write } for  pid=7737 comm="syz-executor0" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_fib_lookup_socket permissive=1
keychord: unsupported version 0
keychord: unsupported version 0
FAULT_FLAG_ALLOW_RETRY missing 30
CPU: 0 PID: 7823 Comm: syz-executor6 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 7747d3f08e12057d ffff8800b44f7970 ffffffff81d0408d
 ffff8801d234f200 1ffff1001689ef3b ffff8800b44f7af8 0000000000000000
 0000000000000000 ffff8800b44f7b20 ffffffff81607305 ffffffff81237410
Call Trace:
 [<ffffffff81d0408d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0408d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81607305>] handle_userfault+0x715/0xf50 fs/userfaultfd.c:316
 [<ffffffff814a2d88>] do_anonymous_page mm/memory.c:2731 [inline]
 [<ffffffff814a2d88>] handle_pte_fault mm/memory.c:3295 [inline]
 [<ffffffff814a2d88>] __handle_mm_fault mm/memory.c:3426 [inline]
 [<ffffffff814a2d88>] handle_mm_fault+0x2938/0x3190 mm/memory.c:3455
 [<ffffffff810dc6cb>] __do_page_fault+0x35b/0xa00 arch/x86/mm/fault.c:1245
 [<ffffffff810dcd97>] do_page_fault+0x27/0x30 arch/x86/mm/fault.c:1308
 [<ffffffff83774d88>] page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1033
 [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
SELinux: unrecognized netlink message: protocol=4 nlmsg_type=24 sclass=netlink_tcpdiag_socket
SELinux: unrecognized netlink message: protocol=4 nlmsg_type=24 sclass=netlink_tcpdiag_socket
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
audit: type=1326 audit(1521940825.052:21): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=7995 comm="syz-executor4" exe="/root/syz-executor4" sig=9 arch=c000003e syscall=202 compat=0 ip=0x454239 code=0x0
audit: type=1326 audit(1521940825.112:22): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=7995 comm="syz-executor4" exe="/root/syz-executor4" sig=9 arch=c000003e syscall=202 compat=0 ip=0x454239 code=0x0
device lo left promiscuous mode
binder: 8286:8289 unknown command -4354173
binder: 8286:8289 ioctl c0306201 2000a000 returned -22
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
binder: 8286:8289 ioctl c0306201 2000afd0 returned -14
binder_alloc: binder_alloc_mmap_handler: 8286 20000000-20002000 already mapped failed -16
binder: BINDER_SET_CONTEXT_MGR already set
binder: 8286:8289 ioctl 40046207 0 returned -16
binder: 8286:8289 unknown command -4354173
binder: 8286:8289 ioctl c0306201 2000a000 returned -22
binder: 8286:8289 ioctl c0306201 2000afd0 returned -14
binder: 8340:8343 ioctl c0306201 20001140 returned -14
binder: 8340:8343 unknown command 25352
binder: 8340:8343 ioctl c0306201 2000a000 returned -22
binder_alloc: binder_alloc_mmap_handler: 8340 20000000-20002000 already mapped failed -16
binder: BINDER_SET_CONTEXT_MGR already set
binder: 8340:8347 ioctl c0306201 20001140 returned -14
binder: 8340:8346 unknown command 0
binder: 8340:8346 ioctl c0306201 2000a000 returned -22
binder_alloc: 8340: binder_alloc_buf, no vma
binder: 8340:8343 ioctl 40046207 0 returned -16
binder: 8340:8347 transaction failed 29189/-3, size 0-0 line 3128
binder: send failed reply for transaction 23 to 8340:8343
binder: undelivered TRANSACTION_ERROR: 29189
BUG: using __this_cpu_read() in preemptible [00000000] code: syz-executor6/8392
caller is __this_cpu_preempt_check+0x1c/0x20 lib/smp_processor_id.c:62
CPU: 1 PID: 8392 Comm: syz-executor6 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 c19a49edd0be0e9a ffff8801ca53f6b8 ffffffff81d0408d
 0000000000000001 ffffffff839fe5a0 ffffffff83d0be20 ffff8801c1890000
 0000000000000003 ffff8801ca53f6f8 ffffffff81d63fe4 ffff8801ca53f710
Call Trace:
 [<ffffffff81d0408d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0408d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81d63fe4>] check_preemption_disabled+0x1d4/0x200 lib/smp_processor_id.c:46
 [<ffffffff81d6404c>] __this_cpu_preempt_check+0x1c/0x20 lib/smp_processor_id.c:62
 [<ffffffff832e2f08>] ipcomp_alloc_tfms net/xfrm/xfrm_ipcomp.c:286 [inline]
 [<ffffffff832e2f08>] ipcomp_init_state+0x188/0x980 net/xfrm/xfrm_ipcomp.c:363
 [<ffffffff833eb945>] ipcomp6_init_state+0xb5/0x820 net/ipv6/ipcomp6.c:165
 [<ffffffff832c1817>] __xfrm_init_state+0x3e7/0xb30 net/xfrm/xfrm_state.c:2058
 [<ffffffff832c1f7a>] xfrm_init_state+0x1a/0x20 net/xfrm/xfrm_state.c:2084
 [<ffffffff8344681b>] pfkey_msg2xfrm_state net/key/af_key.c:1289 [inline]
 [<ffffffff8344681b>] pfkey_add+0x1fbb/0x3490 net/key/af_key.c:1506
 [<ffffffff8344a45b>] pfkey_process+0x68b/0x750 net/key/af_key.c:2834
 [<ffffffff8344bcb9>] pfkey_sendmsg+0x3a9/0x760 net/key/af_key.c:3678
 [<ffffffff82deba6a>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82deba6a>] sock_sendmsg+0xca/0x110 net/socket.c:635
 [<ffffffff82ded641>] ___sys_sendmsg+0x6c1/0x7c0 net/socket.c:1962
 [<ffffffff82def693>] __sys_sendmsg+0xd3/0x190 net/socket.c:1996
 [<ffffffff82def77d>] SYSC_sendmsg net/socket.c:2007 [inline]
 [<ffffffff82def77d>] SyS_sendmsg+0x2d/0x50 net/socket.c:2003
 [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
binder: 8541:8544 ioctl c0306201 20007000 returned -14
binder: 8541:8552 got reply transaction with no transaction stack
binder: 8541:8552 transaction failed 29201/-71, size 0-0 line 2921
binder: BINDER_SET_CONTEXT_MGR already set
binder: 8541:8553 ioctl 40046207 0 returned -16
binder: 8541:8552 ioctl c0306201 20007000 returned -14
binder: 8541:8557 got reply transaction with no transaction stack
binder: 8541:8557 transaction failed 29201/-71, size 0-0 line 2921
binder: undelivered TRANSACTION_ERROR: 29201
binder: undelivered TRANSACTION_ERROR: 29201