binder: 13792:13795 ioctl 40046207 0 returned -16
======================================================
[ INFO: possible circular locking dependency detected ]
4.4.174+ #4 Not tainted
-------------------------------------------------------
syz-executor.2/13800 is trying to acquire lock:
 (&pipe->mutex/1){+.+.+.}, at: [  559.402625] binder: BINDER_SET_CONTEXT_MGR already set
binder: 13812:13814 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13812:13814 transaction failed 29189/-3, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13812:13814 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13812:13816 transaction failed 29189/-3, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13818:13821 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13818:13821 transaction failed 29189/-3, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13818:13822 ioctl 40046207 0 returned -16
[<ffffffff814b28fd>] __pipe_lock fs/pipe.c:86 [inline]
[<ffffffff814b28fd>] fifo_open+0x15d/0xa00 fs/pipe.c:896
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13825:13826 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13825:13826 transaction failed 29189/-3, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13825:13826 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13825:13828 transaction failed 29189/-3, size 96-24 line 3137

but task is already holding lock:
 ([  559.551337] binder: BINDER_SET_CONTEXT_MGR already set
binder: 13831:13833 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13831:13833 transaction failed 29189/-3, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13831:13833 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13831:13835 transaction failed 29189/-3, size 96-24 line 3137
&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff814acb45>] prepare_bprm_creds+0x55/0x120 fs/exec.c:1225

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

binder: BINDER_SET_CONTEXT_MGR already set
binder: 13839:13842 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13839:13842 transaction failed 29189/-3, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13839:13842 ioctl 40046207 0 returned -16
binder_alloc: 13792: binder_alloc_buf, no vma
binder: 13839:13845 transaction failed 29189/-3, size 96-24 line 3137
       [<ffffffff81205f6e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff8270e5a2>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8270e5a2>] mutex_lock_interruptible_nested+0xd2/0xce0 kernel/locking/mutex.c:650
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
       [<ffffffff815e7f78>] proc_pid_attr_write+0x1a8/0x2a0 fs/proc/base.c:2524
       [<ffffffff81496916>] __vfs_write+0x116/0x3d0 fs/read_write.c:491
       [<ffffffff81496ce2>] __kernel_write+0x112/0x370 fs/read_write.c:513
       [<ffffffff81532e6d>] write_pipe_buf+0x15d/0x1f0 fs/splice.c:1074
       [<ffffffff81533b6e>] splice_from_pipe_feed fs/splice.c:776 [inline]
       [<ffffffff81533b6e>] __splice_from_pipe+0x37e/0x7a0 fs/splice.c:901
       [<ffffffff81536be8>] splice_from_pipe+0x108/0x170 fs/splice.c:936
       [<ffffffff81536cdc>] default_file_splice_write+0x3c/0x80 fs/splice.c:1086
       [<ffffffff81537d31>] do_splice_from fs/splice.c:1128 [inline]
       [<ffffffff81537d31>] do_splice fs/splice.c:1404 [inline]
       [<ffffffff81537d31>] SYSC_splice fs/splice.c:1707 [inline]
       [<ffffffff81537d31>] SyS_splice+0xd71/0x13a0 fs/splice.c:1690
       [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81202d86>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff81202d86>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff81202d86>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff81202d86>] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213
       [<ffffffff81205f6e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff8270c191>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8270c191>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
       [<ffffffff814b28fd>] __pipe_lock fs/pipe.c:86 [inline]
       [<ffffffff814b28fd>] fifo_open+0x15d/0xa00 fs/pipe.c:896
       [<ffffffff8149154f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
       [<ffffffff81494d3b>] vfs_open+0x10b/0x210 fs/open.c:862
       [<ffffffff814c5ddf>] do_last fs/namei.c:3269 [inline]
       [<ffffffff814c5ddf>] path_openat+0x136f/0x4470 fs/namei.c:3406
       [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
       [<ffffffff814a7c8c>] do_open_execat+0x10c/0x6e0 fs/exec.c:805
       [<ffffffff814ad306>] do_execveat_common.isra.0+0x6f6/0x1e90 fs/exec.c:1577
       [<ffffffff814af422>] do_execve fs/exec.c:1683 [inline]
       [<ffffffff814af422>] SYSC_execve fs/exec.c:1764 [inline]
       [<ffffffff814af422>] SyS_execve+0x42/0x50 fs/exec.c:1759
       [<ffffffff82718ef5>] return_from_execve+0x0/0x23

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&sig->cred_guard_mutex);
                               lock(&pipe->mutex/1);
                               lock(&sig->cred_guard_mutex);
  lock(&pipe->mutex/1);

 *** DEADLOCK ***

1 lock held by syz-executor.2/13800:
 #0:  (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff814acb45>] prepare_bprm_creds+0x55/0x120 fs/exec.c:1225

stack backtrace:
CPU: 0 PID: 13800 Comm: syz-executor.2 Not tainted 4.4.174+ #4
 0000000000000000 d6d44ae3a289568f ffff8801c0acf530 ffffffff81aad1a1
 ffffffff84057a80 ffff8801d4e297c0 ffffffff83abd2b0 ffffffff83ab6860
 ffffffff83abd2b0 ffff8801c0acf580 ffffffff813abcda ffff8801c0acf660
Call Trace:
 [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff813abcda>] print_circular_bug.cold+0x2f7/0x44e kernel/locking/lockdep.c:1226
 [<ffffffff81202d86>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff81202d86>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff81202d86>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff81202d86>] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213
 [<ffffffff81205f6e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff8270c191>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff8270c191>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
 [<ffffffff814b28fd>] __pipe_lock fs/pipe.c:86 [inline]
 [<ffffffff814b28fd>] fifo_open+0x15d/0xa00 fs/pipe.c:896
 [<ffffffff8149154f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
 [<ffffffff81494d3b>] vfs_open+0x10b/0x210 fs/open.c:862
 [<ffffffff814c5ddf>] do_last fs/namei.c:3269 [inline]
 [<ffffffff814c5ddf>] path_openat+0x136f/0x4470 fs/namei.c:3406
 [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff814a7c8c>] do_open_execat+0x10c/0x6e0 fs/exec.c:805
 [<ffffffff814ad306>] do_execveat_common.isra.0+0x6f6/0x1e90 fs/exec.c:1577
 [<ffffffff814af422>] do_execve fs/exec.c:1683 [inline]
 [<ffffffff814af422>] SYSC_execve fs/exec.c:1764 [inline]
 [<ffffffff814af422>] SyS_execve+0x42/0x50 fs/exec.c:1759
 [<ffffffff82718ef5>] stub_execve+0x5/0x5 arch/x86/entry/entry_64.S:440
binder_alloc: 13873: binder_alloc_buf, no vma
binder: 13873:13886 transaction failed 29189/-3, size 96-24 line 3137
binder: undelivered TRANSACTION_ERROR: 29189
binder: 13908:13912 unknown command 536871232
binder: 13908:13912 ioctl c0306201 20000040 returned -22
binder: 13908:13921 unknown command 536871232
binder: 13908:13921 ioctl c0306201 20000040 returned -22
binder: 13940:13942 got transaction with unaligned buffers size, 214
binder: 13940:13942 transaction failed 29201/-22, size 96-24 line 3181
binder: undelivered TRANSACTION_ERROR: 29201
binder: 13940:13942 got transaction with unaligned buffers size, 214
binder: 13940:13942 transaction failed 29201/-22, size 96-24 line 3181
binder: undelivered TRANSACTION_ERROR: 29201
binder_alloc: 13969: binder_alloc_buf size -413005597459674000 failed, no address space
binder_alloc: allocated: 0 (num: 0 largest: 0), free: 8192 (num: 1 largest: 8192)
binder: 13969:13977 transaction failed 29201/-28, size 96-24 line 3137
binder: BINDER_SET_CONTEXT_MGR already set
binder: 13969:13977 ioctl 40046207 0 returned -16
binder: undelivered TRANSACTION_ERROR: 29201
binder: 13969:13984 transaction failed 29189/-22, size 96-24 line 3014
binder: undelivered TRANSACTION_ERROR: 29189
binder_alloc: 13996: binder_alloc_buf, no vma
binder: 13996:14003 transaction failed 29189/-3, size 96-24 line 3137
binder: undelivered TRANSACTION_ERROR: 29189
binder: 13996:14019 transaction failed 29189/-22, size 96-24 line 3014
binder: undelivered TRANSACTION_ERROR: 29189
binder: 14027:14029 got transaction with unaligned buffers size, 9
binder: 14027:14029 transaction failed 29201/-22, size 96-24 line 3181
binder: undelivered TRANSACTION_ERROR: 29201
binder: 14027:14034 got transaction with unaligned buffers size, 9
binder: 14027:14034 transaction failed 29201/-22, size 96-24 line 3181
binder: undelivered TRANSACTION_ERROR: 29201
binder_alloc: 14038: binder_alloc_buf size 3978709506094217136 failed, no address space
binder_alloc: allocated: 0 (num: 0 largest: 0), free: 8192 (num: 1 largest: 8192)
binder: 14038:14042 transaction failed 29201/-28, size 96-24 line 3137
binder: undelivered TRANSACTION_ERROR: 29201
binder_alloc: 14038: binder_alloc_buf size 3978709506094217136 failed, no address space
binder_alloc: allocated: 0 (num: 0 largest: 0), free: 8192 (num: 1 largest: 8192)
binder: 14038:14045 transaction failed 29201/-28, size 96-24 line 3137
binder: undelivered TRANSACTION_ERROR: 29201