======================================================
[ INFO: possible circular locking dependency detected ]
4.4.119-g024f962 #27 Not tainted
-------------------------------------------------------
syz-executor3/9300 is trying to acquire lock:
 (&mm->mmap_sem){++++++}, at: [<ffffffff81495644>] __might_fault+0xe4/0x1d0 mm/memory.c:3809

but task is already holding lock:
 (ashmem_mutex){+.+.+.}, at: [<ffffffff82c626b7>] ashmem_pin_unpin drivers/staging/android/ashmem.c:701 [inline]
 (ashmem_mutex){+.+.+.}, at: [<ffffffff82c626b7>] ashmem_ioctl+0x367/0xfa0 drivers/staging/android/ashmem.c:778

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
       [<ffffffff8376a06b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8376a06b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
       [<ffffffff82c61273>] ashmem_mmap+0x53/0x400 drivers/staging/android/ashmem.c:366
       [<ffffffff814b0e0f>] mmap_region+0x94f/0x1250 mm/mmap.c:1664
       [<ffffffff814b1c0d>] do_mmap+0x4fd/0x9d0 mm/mmap.c:1441
       [<ffffffff8147008e>] do_mmap_pgoff include/linux/mm.h:1915 [inline]
       [<ffffffff8147008e>] vm_mmap_pgoff+0x16e/0x1c0 mm/util.c:296
       [<ffffffff814afddf>] SYSC_mmap_pgoff mm/mmap.c:1491 [inline]
       [<ffffffff814afddf>] 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
       [<ffffffff83774faa>] sysenter_flags_fixed+0xd/0x17

       [<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
       [<ffffffff814956aa>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
       [<ffffffff82c62704>] copy_from_user arch/x86/include/asm/uaccess.h:724 [inline]
       [<ffffffff82c62704>] ashmem_pin_unpin drivers/staging/android/ashmem.c:706 [inline]
       [<ffffffff82c62704>] ashmem_ioctl+0x3b4/0xfa0 drivers/staging/android/ashmem.c:778
       [<ffffffff82c6332e>] compat_ashmem_ioctl+0x3e/0x50 drivers/staging/android/ashmem.c:809
       [<ffffffff8161e57a>] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline]
       [<ffffffff8161e57a>] compat_SyS_ioctl+0x28a/0x2540 fs/compat_ioctl.c:1544
       [<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
       [<ffffffff83774faa>] sysenter_flags_fixed+0xd/0x17

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(ashmem_mutex);
                               lock(&mm->mmap_sem);
                               lock(ashmem_mutex);
  lock(&mm->mmap_sem);

 *** DEADLOCK ***

1 lock held by syz-executor3/9300:
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c626b7>] ashmem_pin_unpin drivers/staging/android/ashmem.c:701 [inline]
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c626b7>] ashmem_ioctl+0x367/0xfa0 drivers/staging/android/ashmem.c:778

stack backtrace:
CPU: 0 PID: 9300 Comm: syz-executor3 Not tainted 4.4.119-g024f962 #27
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 826a3de8fdf786fb ffff8800ae75f8a8 ffffffff81d0402d
 ffffffff851a0010 ffffffff851a0010 ffffffff851beb20 ffff8801d07020f8
 ffff8801d0701800 ffff8800ae75f8f0 ffffffff81233ba1 ffff8801d07020f8
Call Trace:
 [<ffffffff81d0402d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0402d>] 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
 [<ffffffff814956aa>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
 [<ffffffff82c62704>] copy_from_user arch/x86/include/asm/uaccess.h:724 [inline]
 [<ffffffff82c62704>] ashmem_pin_unpin drivers/staging/android/ashmem.c:706 [inline]
 [<ffffffff82c62704>] ashmem_ioctl+0x3b4/0xfa0 drivers/staging/android/ashmem.c:778
 [<ffffffff82c6332e>] compat_ashmem_ioctl+0x3e/0x50 drivers/staging/android/ashmem.c:809
 [<ffffffff8161e57a>] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline]
 [<ffffffff8161e57a>] compat_SyS_ioctl+0x28a/0x2540 fs/compat_ioctl.c:1544
 [<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
 [<ffffffff83774faa>] sysenter_flags_fixed+0xd/0x17
binder: 9389:9394 transaction failed 29189/-22, size 24-8 line 3005
audit_printk_skb: 54 callbacks suppressed
audit: type=1400 audit(1519903009.131:86): avc:  denied  { set_context_mgr } for  pid=9389 comm="syz-executor7" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=binder permissive=1
binder_alloc: binder_alloc_mmap_handler: 9389 2000c000-2000e000 already mapped failed -16
audit: type=1400 audit(1519903009.301:87): avc:  denied  { call } for  pid=9389 comm="syz-executor7" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=binder permissive=1
binder_alloc: 9389: binder_alloc_buf, no vma
binder: 9389:9411 transaction failed 29189/-3, size 24-8 line 3128
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
audit: type=1400 audit(1519903009.981:88): avc:  denied  { create } for  pid=9492 comm="syz-executor7" 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
audit: type=1400 audit(1519903010.041:89): avc:  denied  { create } for  pid=9492 comm="syz-executor7" 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
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
binder: 9529:9537 unknown command 5
binder: 9529:9541 unknown command 5
binder: 9529:9537 ioctl c0306201 20000200 returned -22
binder: 9529:9541 ioctl c0306201 20000200 returned -22
audit: type=1400 audit(1519903011.901:90): avc:  denied  { create } for  pid=9699 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
audit: type=1400 audit(1519903011.951:91): avc:  denied  { create } for  pid=9699 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
audit: type=1400 audit(1519903012.011:92): avc:  denied  { setopt } for  pid=9699 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: unrecognized netlink message: protocol=0 nlmsg_type=51300 sclass=netlink_route_socket
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=51300 sclass=netlink_route_socket
audit: type=1400 audit(1519903017.291:93): avc:  denied  { create } for  pid=10294 comm="syz-executor3" 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(1519903017.371:94): avc:  denied  { create } for  pid=10294 comm="syz-executor3" 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