======================================================
[ INFO: possible circular locking dependency detected ]
4.4.120-gd63fdf6 #28 Not tainted
-------------------------------------------------------
syz-executor3/6948 is trying to acquire lock:
 (&mm->mmap_sem){++++++}, at: [<ffffffff81495684>] __might_fault+0xe4/0x1d0 mm/memory.c:3809

but task is already holding lock:
 (ashmem_mutex){+.+.+.}, at: [<ffffffff82c628a7>] ashmem_pin_unpin drivers/staging/android/ashmem.c:701 [inline]
 (ashmem_mutex){+.+.+.}, at: [<ffffffff82c628a7>] 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
       [<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

       [<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
       [<ffffffff814956ea>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
       [<ffffffff82c628f4>] copy_from_user arch/x86/include/asm/uaccess.h:724 [inline]
       [<ffffffff82c628f4>] ashmem_pin_unpin drivers/staging/android/ashmem.c:706 [inline]
       [<ffffffff82c628f4>] ashmem_ioctl+0x3b4/0xfa0 drivers/staging/android/ashmem.c:778
       [<ffffffff81559daa>] vfs_ioctl fs/ioctl.c:43 [inline]
       [<ffffffff81559daa>] do_vfs_ioctl+0x7aa/0xee0 fs/ioctl.c:607
       [<ffffffff8155a56f>] SYSC_ioctl fs/ioctl.c:622 [inline]
       [<ffffffff8155a56f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
       [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98

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-executor3/6948:
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c628a7>] ashmem_pin_unpin drivers/staging/android/ashmem.c:701 [inline]
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c628a7>] ashmem_ioctl+0x367/0xfa0 drivers/staging/android/ashmem.c:778

stack backtrace:
CPU: 0 PID: 6948 Comm: syz-executor3 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 5dc923b4fe6d62e1 ffff8801d6dbf9b8 ffffffff81d0408d
 ffffffff8519fe60 ffffffff8519fe60 ffffffff851be970 ffff8800b97368f8
 ffff8800b9736000 ffff8801d6dbfa00 ffffffff81233ba1 ffff8800b97368f8
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
 [<ffffffff814956ea>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
 [<ffffffff82c628f4>] copy_from_user arch/x86/include/asm/uaccess.h:724 [inline]
 [<ffffffff82c628f4>] ashmem_pin_unpin drivers/staging/android/ashmem.c:706 [inline]
 [<ffffffff82c628f4>] ashmem_ioctl+0x3b4/0xfa0 drivers/staging/android/ashmem.c:778
 [<ffffffff81559daa>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff81559daa>] do_vfs_ioctl+0x7aa/0xee0 fs/ioctl.c:607
 [<ffffffff8155a56f>] SYSC_ioctl fs/ioctl.c:622 [inline]
 [<ffffffff8155a56f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
 [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
audit_printk_skb: 15 callbacks suppressed
audit: type=1400 audit(1520554309.116:19): avc:  denied  { getopt } for  pid=7105 comm="syz-executor2" 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(1520554309.496:20): avc:  denied  { create } for  pid=7175 comm="syz-executor6" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:unlabeled_t:s0 tclass=key permissive=1
netlink: 8 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor5'.
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 7310 Comm: syz-executor6 Not tainted 4.4.120-gd63fdf6 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
audit: type=1400 audit(1520554310.016:21): avc:  denied  { set_context_mgr } for  pid=7314 comm="syz-executor2" 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: 7314 invalid dec weak, ref 9 desc 0 s 1 w 0
binder: BINDER_SET_CONTEXT_MGR already set
binder: 7314:7320 ioctl 40046207 0 returned -16
task: ffff8800b9588000 task.stack: ffff8800b99d0000
RIP: 0010:[<ffffffff831aa241>] [   52.562124] audit: type=1400 audit(1520554310.076:22): avc:  denied  { create } for  pid=7326 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
audit: type=1400 audit(1520554310.076:23): avc:  denied  { write } for  pid=7326 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
audit: type=1400 audit(1520554310.076:24): avc:  denied  { ioctl } for  pid=7326 comm="syz-executor5" path="socket:[17682]" dev="sockfs" ino=17682 ioctlcmd=54d7 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(1520554310.086:25): avc:  denied  { create } for  pid=7326 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
audit: type=1400 audit(1520554310.086:26): avc:  denied  { write } for  pid=7326 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
audit: type=1400 audit(1520554310.086:27): avc:  denied  { ioctl } for  pid=7326 comm="syz-executor5" path="socket:[17688]" dev="sockfs" ino=17688 ioctlcmd=54d7 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
 [<ffffffff831aa241>] __xfrm_policy_check2 include/net/xfrm.h:1070 [inline]
 [<ffffffff831aa241>] xfrm_policy_check include/net/xfrm.h:1076 [inline]
 [<ffffffff831aa241>] xfrm4_policy_check include/net/xfrm.h:1081 [inline]
 [<ffffffff831aa241>] udp_queue_rcv_skb+0x191/0x1560 net/ipv4/udp.c:1517
RSP: 0018:ffff8800b99d7928  EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff8800a8f40000 RCX: ffffffff831aa228
RDX: 000000000000000c RSI: ffffc90003ad0000 RDI: 0000000000000060
RBP: ffff8800b99d7968 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff1001733aef6 R12: ffff8800b9b53140
R13: 0000000000000001 R14: 0000000000000000 R15: ffff8800b9b53198
FS:  00007f0bd7ae8700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000a3eb48 CR3: 00000001d6222000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8800a8f40088 ffff880000000001 ffff8800a8f40088 dffffc0000000000
 ffff8800a8f40000 0000000000000000 ffffed00151e8086 ffff8800b9b53140
 ffff8800b99d79d8 ffffffff82df8cb6 ffff8800a8f40188 ffff8800a8f40190
Call Trace:
 [<ffffffff82df8cb6>] sk_backlog_rcv include/net/sock.h:871 [inline]
 [<ffffffff82df8cb6>] __release_sock net/core/sock.c:2023 [inline]
 [<ffffffff82df8cb6>] release_sock+0x176/0x510 net/core/sock.c:2473
 [<ffffffff831a3854>] udp_sendmsg+0x15c4/0x1c30 net/ipv4/udp.c:1105
 [<ffffffff831d7d4c>] inet_sendmsg+0x2bc/0x4c0 net/ipv4/af_inet.c:755
 [<ffffffff82deba6a>] sock_sendmsg_nosec net/socket.c:625 [inline]
 [<ffffffff82deba6a>] sock_sendmsg+0xca/0x110 net/socket.c:635
 [<ffffffff82dec9b8>] SYSC_sendto+0x2c8/0x340 net/socket.c:1665
 [<ffffffff82deeeb0>] SyS_sendto+0x40/0x50 net/socket.c:1633
 [<ffffffff8377395f>] entry_SYSCALL_64_fastpath+0x1c/0x98
Code: 74 24 58 41 f6 c6 01 0f 85 7f 07 00 00 e8 28 6b 1b fe 49 83 e6 fe 48 b8 00 00 00 00 00 fc ff df 49 8d 7e 60 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 01 0f 8e 9f 0b 00 00 41 f6 46 60 04 
RIP  [<ffffffff831aa241>] __xfrm_policy_check2 include/net/xfrm.h:1070 [inline]
RIP  [<ffffffff831aa241>] xfrm_policy_check include/net/xfrm.h:1076 [inline]
RIP  [<ffffffff831aa241>] xfrm4_policy_check include/net/xfrm.h:1081 [inline]
RIP  [<ffffffff831aa241>] udp_queue_rcv_skb+0x191/0x1560 net/ipv4/udp.c:1517
 RSP <ffff8800b99d7928>
---[ end trace 6fd3d33e7a070d42 ]---