======================================================
[ INFO: possible circular locking dependency detected ]
4.4.120-gd63fdf6 #29 Not tainted
-------------------------------------------------------
syz-executor5/6964 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:
 (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
       [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
       [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
       [<ffffffff837752ea>] sysenter_flags_fixed+0xd/0x17

       [<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
       [<ffffffff8151e6db>] vfs_llseek fs/read_write.c:260 [inline]
       [<ffffffff8151e6db>] SYSC_lseek fs/read_write.c:285 [inline]
       [<ffffffff8151e6db>] SyS_lseek fs/read_write.c:276 [inline]
       [<ffffffff8151e6db>] C_SYSC_lseek fs/read_write.c:297 [inline]
       [<ffffffff8151e6db>] compat_SyS_lseek+0xeb/0x170 fs/read_write.c:295
       [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
       [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
       [<ffffffff837752ea>] sysenter_flags_fixed+0xd/0x17

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-executor5/6964:
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c62016>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330

stack backtrace:
CPU: 0 PID: 6964 Comm: syz-executor5 Not tainted 4.4.120-gd63fdf6 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 e19df4c0328f8ea0 ffff8801c9d9fa58 ffffffff81d0408d
 ffffffff8519fe60 ffffffff851a99a0 ffffffff851be970 ffff8801c8bc20f8
 ffff8801c8bc1800 ffff8801c9d9faa0 ffffffff81233ba1 ffff8801c8bc20f8
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
 [<ffffffff8151e6db>] vfs_llseek fs/read_write.c:260 [inline]
 [<ffffffff8151e6db>] SYSC_lseek fs/read_write.c:285 [inline]
 [<ffffffff8151e6db>] SyS_lseek fs/read_write.c:276 [inline]
 [<ffffffff8151e6db>] C_SYSC_lseek fs/read_write.c:297 [inline]
 [<ffffffff8151e6db>] compat_SyS_lseek+0xeb/0x170 fs/read_write.c:295
 [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
 [<ffffffff837752ea>] sysenter_flags_fixed+0xd/0x17
SELinux: unrecognized netlink message: protocol=9 nlmsg_type=24 sclass=netlink_audit_socket
SELinux: unrecognized netlink message: protocol=9 nlmsg_type=24 sclass=netlink_audit_socket
netlink: 11 bytes leftover after parsing attributes in process `syz-executor4'.
audit: type=1400 audit(1521897555.488:19): avc:  denied  { read } for  pid=7315 comm="syz-executor4" path="socket:[16672]" dev="sockfs" ino=16672 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1
netlink: 11 bytes leftover after parsing attributes in process `syz-executor4'.
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=63670 sclass=netlink_route_socket
IPVS: length: 413 != 24
netlink: 12 bytes leftover after parsing attributes in process `syz-executor4'.
netlink: 12 bytes leftover after parsing attributes in process `syz-executor4'.
IPVS: length: 413 != 24
binder: 7599:7601 transaction failed 29189/-22, size 0-0 line 3005
binder: undelivered TRANSACTION_ERROR: 29189
binder: 7724:7731 unknown command 0
binder: 7724:7731 ioctl c0306201 20000000 returned -22
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
binder: 7724:7731 unknown command 0
binder: 7724:7731 ioctl c0306201 20000000 returned -22
binder: 8007:8009 ioctl c0306201 2000ffd0 returned -14
binder: BINDER_SET_CONTEXT_MGR already set
binder: 8007:8027 ioctl 40046207 0 returned -16
binder: 8007:8009 ioctl c0306201 2000ffd0 returned -14
binder: release 8007:8009 transaction 21 in, still active
binder: send failed reply for transaction 21 to 8007:8027
binder: undelivered TRANSACTION_COMPLETE
binder: undelivered TRANSACTION_ERROR: 29189
device bridge0 entered promiscuous mode
binder: 8134:8136 BC_REQUEST_DEATH_NOTIFICATION invalid ref 0
binder: 8134:8147 BC_REQUEST_DEATH_NOTIFICATION invalid ref 0
binder_alloc: 8227: binder_alloc_buf size 4323279720415280 failed, no address space
binder_alloc: allocated: 0 (num: 0 largest: 0), free: 12288 (num: 1 largest: 12288)
binder: 8227:8230 transaction failed 29201/-28, size 40-4323279720415240 line 3128
binder: 8227:8238 BC_CLEAR_DEATH_NOTIFICATION death notification not active
binder: BINDER_SET_CONTEXT_MGR already set
binder: 8227:8238 ioctl 40046207 0 returned -16
binder_alloc: 8227: binder_alloc_buf, no vma
binder: 8227:8230 transaction failed 29189/-3, size 40-4323279720415240 line 3128
binder: 8227:8248 BC_CLEAR_DEATH_NOTIFICATION death notification not active
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29201
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
audit: type=1400 audit(1521897560.088:20): avc:  denied  { getopt } for  pid=8391 comm="syz-executor6" 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
audit: type=1400 audit(1521897560.148:21): avc:  denied  { getattr } for  pid=8391 comm="syz-executor6" path="socket:[19562]" dev="sockfs" ino=19562 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
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket
audit: type=1400 audit(1521897560.728:22): avc:  denied  { bind } for  pid=8593 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_netfilter_socket permissive=1
binder: 8622:8635 ioctl c0306201 200001c0 returned -11
binder: 8622:8635 transaction failed 29189/-22, size 0-0 line 3005
SELinux: unrecognized netlink message: protocol=4 nlmsg_type=17 sclass=netlink_tcpdiag_socket
SELinux: unrecognized netlink message: protocol=4 nlmsg_type=17 sclass=netlink_tcpdiag_socket
keychord: using input dev AT Translated Set 2 keyboard for fevent
keychord: Insufficient bytes present for keycount 37
binder: 8800:8813 ioctl c0306201 2000ffd0 returned -14
binder: BINDER_SET_CONTEXT_MGR already set
binder: 8800:8823 ioctl 40046207 0 returned -16
binder: 8800:8813 ioctl c0306201 2000ffd0 returned -14
binder_alloc: 8800: binder_alloc_buf, no vma
binder: 8800:8823 transaction failed 29189/-3, size 0-0 line 3128
binder: undelivered TRANSACTION_ERROR: 29189
binder: release 8800:8813 transaction 29 in, still active
binder: send failed reply for transaction 29 to 8800:8823
binder: undelivered TRANSACTION_COMPLETE
binder: undelivered TRANSACTION_ERROR: 29189
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=31257 sclass=netlink_route_socket
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=31257 sclass=netlink_route_socket
SELinux: unrecognized netlink message: protocol=9 nlmsg_type=37952 sclass=netlink_audit_socket
SELinux: unrecognized netlink message: protocol=9 nlmsg_type=37952 sclass=netlink_audit_socket
binder: 9073:9076 IncRefs 0 refcount change on invalid ref 4 ret -22
binder: 9073:9076 ERROR: BC_REGISTER_LOOPER called after BC_ENTER_LOOPER
binder: BINDER_SET_CONTEXT_MGR already set
binder: 9073:9081 ioctl 40046207 0 returned -16
binder: 9073:9076 ioctl c0306201 20007fd0 returned -14
binder: release 9073:9081 transaction 33 out, still active
binder: undelivered TRANSACTION_COMPLETE
binder: send failed reply for transaction 32 to 9073:9081
binder: undelivered TRANSACTION_COMPLETE
binder: undelivered TRANSACTION_ERROR: 29189
binder: send failed reply for transaction 33, target dead