======================================================
[ INFO: possible circular locking dependency detected ]
4.4.120-gd63fdf6 #29 Not tainted
-------------------------------------------------------
syz-executor3/5293 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-executor3/5293:
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c62016>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330

stack backtrace:
CPU: 1 PID: 5293 Comm: syz-executor3 Not tainted 4.4.120-gd63fdf6 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 b182ec3f6f841e80 ffff8800aadc7a58 ffffffff81d0408d
 ffffffff851a0010 ffffffff851a9d00 ffffffff851be610 ffff8800ab2950f8
 ffff8800ab294800 ffff8800aadc7aa0 ffffffff81233ba1 ffff8800ab2950f8
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
audit: type=1400 audit(1521664258.113:8): avc:  denied  { create } for  pid=5348 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_netfilter_socket permissive=1
audit: type=1400 audit(1521664258.133:9): avc:  denied  { ioctl } for  pid=5348 comm="syz-executor6" path="socket:[12038]" dev="sockfs" ino=12038 ioctlcmd=8903 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
BUG: using __this_cpu_read() in preemptible [00000000] code: syz-executor1/5414
caller is __this_cpu_preempt_check+0x1c/0x20 lib/smp_processor_id.c:62
CPU: 1 PID: 5414 Comm: syz-executor1 Not tainted 4.4.120-gd63fdf6 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 8881394fb42f777f ffff8800aadc7648 ffffffff81d0408d
 0000000000000001 ffffffff839fe5a0 ffffffff83d0be20 ffff8801c4831800
 0000000000000003 ffff8800aadc7688 ffffffff81d63fe4 ffff8800aadc76a0
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
 [<ffffffff8324ac70>] ipcomp4_init_state+0xb0/0x7d0 net/ipv4/ipcomp.c:137
 [<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
 [<ffffffff82eda56a>] C_SYSC_sendmsg net/compat.c:720 [inline]
 [<ffffffff82eda56a>] compat_SyS_sendmsg+0x2a/0x40 net/compat.c:718
 [<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
sock: sock_set_timeout: `syz-executor1' (pid 5521) tries to set negative timeout
sock: sock_set_timeout: `syz-executor1' (pid 5521) tries to set negative timeout
IPVS: Creating netns size=2552 id=9
IPVS: Creating netns size=2552 id=10
audit: type=1400 audit(1521664259.523:10): avc:  denied  { write } for  pid=5575 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(1521664259.533:11): avc:  denied  { set_context_mgr } for  pid=5583 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=binder permissive=1
binder: 5583:5588 unknown command -683646208
binder: 5583:5588 ioctl c0306201 20008000 returned -22
binder: 5583:5588 BC_CLEAR_DEATH_NOTIFICATION death notification not active
audit: type=1400 audit(1521664259.593:12): avc:  denied  { read } for  pid=5575 comm="syz-executor5" path="socket:[13371]" dev="sockfs" ino=13371 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: 12 bytes leftover after parsing attributes in process `syz-executor5'.
binder_alloc: binder_alloc_mmap_handler: 5583 20ffb000-20ffe000 already mapped failed -16
netlink: 3 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 12 bytes leftover after parsing attributes in process `syz-executor5'.
netlink: 3 bytes leftover after parsing attributes in process `syz-executor5'.
binder: BINDER_SET_CONTEXT_MGR already set
binder: 5583:5596 unknown command -683646208
binder: 5583:5605 ioctl 40046207 0 returned -16
binder: 5583:5596 ioctl c0306201 20008000 returned -22
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
sg_write: data in/out 9964/6 bytes for SCSI command 0x0-- guessing data in;
   program syz-executor4 not setting count and/or reply_len properly
binder: 5883:5889 BC_INCREFS_DONE node 4 has no pending increfs request
binder_alloc: binder_alloc_mmap_handler: 5883 20000000-20002000 already mapped failed -16
binder: BINDER_SET_CONTEXT_MGR already set
binder: 5883:5889 ioctl 40046207 0 returned -16
SELinux:  policydb magic number 0x0 does not match expected magic number 0xf97cff8c
SELinux:  policydb magic number 0x0 does not match expected magic number 0xf97cff8c
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=41686 sclass=netlink_route_socket
sd 0:0:1:0: [sg0] tag#91 FAILED Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK
sd 0:0:1:0: [sg0] tag#91 CDB: Test Unit Ready
sd 0:0:1:0: [sg0] tag#91 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#91 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#91 CDB[20]: 00 00 00
audit_printk_skb: 6 callbacks suppressed
audit: type=1401 audit(1521664264.153:15): op=setxattr invalid_context=":"
audit: type=1401 audit(1521664264.203:16): op=setxattr invalid_context=":"
binder: 6495:6500 DecRefs 0 refcount change on invalid ref 2 ret -22
audit: type=1400 audit(1521664264.433:17): avc:  denied  { dyntransition } for  pid=6498 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=process permissive=1
audit: type=1400 audit(1521664264.433:18): avc:  denied  { setattr } for  pid=6498 comm="syz-executor3" name="current" dev="proc" ino=15561 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=file permissive=1
audit: type=1400 audit(1521664264.513:19): avc:  denied  { call } for  pid=6495 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=binder permissive=1
binder: send failed reply for transaction 6 to 6495:6511
binder: 6495:6500 ioctl c0306201 20000180 returned -14
binder: 6495:6511 ioctl c0306201 20000180 returned -14
binder: BINDER_SET_CONTEXT_MGR already set
binder_alloc: binder_alloc_mmap_handler: 6495 20000000-20001000 already mapped failed -16
binder_alloc: 6495: binder_alloc_buf, no vma
binder: 6495:6512 transaction failed 29189/-3, size 0-0 line 3128
binder: 6495:6500 ioctl 40046207 0 returned -16
audit: type=1401 audit(1521664264.613:20): op=fscreate invalid_context=73797374656D5F753A6F626A6563745F723A6E65746C6162656C5F6D676D745F657865635F743A733000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000[   52.999264] netlink: 40 bytes leftover after parsing attributes in process `syz-executor4'.
netlink: 40 bytes leftover after parsing attributes in process `syz-executor4'.
binder: 6878:6884 Acquire 1 refcount change on invalid ref 0 ret -22
binder: 6878:6884 BC_CLEAR_DEATH_NOTIFICATION invalid ref 0
binder: 6878:6884 got reply transaction with no transaction stack
binder: 6878:6884 transaction failed 29201/-71, size 0-0 line 2921
binder: 6878:6894 Acquire 1 refcount change on invalid ref 0 ret -22
binder: 6878:6884 BC_CLEAR_DEATH_NOTIFICATION invalid ref 0
binder: 6878:6884 got reply transaction with no transaction stack
binder: 6878:6884 transaction failed 29201/-71, size 0-0 line 2921
binder: undelivered TRANSACTION_ERROR: 29201
binder: undelivered TRANSACTION_ERROR: 29201