kernel BUG at drivers/android/binder_alloc.c:LINE!

[Eric Biggers]

On Fri, Dec 01, 2017 at 04:22:00PM -0800, syzbot wrote:
> syzkaller has found reproducer for the following crash on
> 3c1c4ddffb58b9e10b3365764fe59546130b3f32
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
> 
> 
> binder: 3087:3087 ERROR: BC_REGISTER_LOOPER called without request
> binder: 3087:3087 ioctl c0306201 2000dfd0 returned -14
> ------------[ cut here ]------------
> kernel BUG at drivers/android/binder_alloc.c:750!
> invalid opcode: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 0 PID: 1404 Comm: kworker/0:2 Not tainted 4.15.0-rc1+ #203
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: events binder_deferred_func
> task: 0000000009b739b6 task.stack: 00000000c1d4442c
> RIP: 0010:binder_alloc_deferred_release+0x146/0xa40
> drivers/android/binder_alloc.c:750
> RSP: 0018:ffff8801d2b16fd8 EFLAGS: 00010293
> RAX: ffff8801d2b08080 RBX: ffff8801d7829300 RCX: ffffffff8403b856
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8801d7829330
> RBP: ffff8801d2b17138 R08: ffffffff8403b7d9 R09: 1ffffffff0e53001
> R10: ffff8801d2b16fc8 R11: ffffffff87489d60 R12: 0000000000000000
> R13: dffffc0000000000 R14: ffff8801d2b17110 R15: ffff8801d7829310
> FS:  0000000000000000(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000006d00a8 CR3: 0000000005e25000 CR4: 00000000001406f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  binder_free_proc drivers/android/binder.c:4200 [inline]
>  binder_proc_dec_tmpref+0x2f3/0x420 drivers/android/binder.c:1833
>  binder_deferred_release drivers/android/binder.c:4858 [inline]
>  binder_deferred_func+0xe22/0x12f0 drivers/android/binder.c:4893
>  process_one_work+0xbfd/0x1be0 kernel/workqueue.c:2112
>  worker_thread+0x223/0x1990 kernel/workqueue.c:2246
>  kthread+0x37a/0x440 kernel/kthread.c:238
>  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441
> Code: e8 00 40 6c fd 49 8d 7f 20 49 8d 5f f0 48 89 fa 48 c1 ea 03 42 80 3c
> 2a 00 0f 85 84 07 00 00 49 83 7f 20 00 74 a9 e8 da 3f 6c fd <0f> 0b 48 8b 9d
> e8 fe ff ff 44 89 a5 bc fe ff ff e8 c5 3f 6c fd
> RIP: binder_alloc_deferred_release+0x146/0xa40
> drivers/android/binder_alloc.c:750 RSP: ffff8801d2b16fd8
> ---[ end trace 616e085d0dbf3c21 ]---
> Kernel panic - not syncing: Fatal exception
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..

This crash stopped occurring in v4.15-rc3, and I verified that it was commit
fb2c445277e which fixed it (thanks Martijn!).  So, telling syzbot so that it can
start reporting similar crashes again:

#syz fix: ANDROID: binder: fix transaction leak.

- Eric