Re: BUG: unable to handle kernel NULL pointer dereference in binder_poll

[Eric Biggers]

On Mon, Dec 18, 2017 at 08:23:01AM -0800, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on
> 6084b576dca2e898f5c101baef151f7bfdbb606d
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.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
> 
> 
> RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000444119
> RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000003
> RBP: 0000000000000005 R08: 0000000000000001 R09: 0000000000000032
> R10: 00000000207a6000 R11: 0000000000000246 R12: 0000000000401e60
> R13: 0000000000401ef0 R14: 0000000000000000 R15: 0000000000000000
> BUG: unable to handle kernel NULL pointer dereference at           (null)
> IP: binder_poll+0x28/0xf0 drivers/android/binder.c:4371
> PGD 2134c1067 P4D 2134c1067 PUD 214180067 PMD 0
> Oops: 0000 [#1] SMP
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 0 PID: 3117 Comm: syzkaller406906 Not tainted 4.15.0-rc3-next-20171214+
> #67
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:binder_poll+0x28/0xf0 drivers/android/binder.c:4371
> RSP: 0018:ffffc900017d3df0 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: ffffc900017d3ef0 RCX: ffffffff820258f3
> RDX: 0000000000000000 RSI: ffffffff83080700 RDI: 0000000000000286
> RBP: ffffc900017d3e20 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffffc900017d3ef0
> R13: ffff8802118fb000 R14: ffffffff82bb9f20 R15: ffff8802140d1c30
> FS:  0000000000deb880(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 0000000216bbc002 CR4: 00000000001606f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  ep_item_poll.isra.10+0x49/0xf0 fs/eventpoll.c:885
>  ep_insert fs/eventpoll.c:1457 [inline]
>  SYSC_epoll_ctl fs/eventpoll.c:2104 [inline]
>  SyS_epoll_ctl+0x884/0x1010 fs/eventpoll.c:1990
>  entry_SYSCALL_64_fastpath+0x1f/0x96
> RIP: 0033:0x444119
> RSP: 002b:00007fffbc6b55b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
> RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000444119
> RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000003
> RBP: 0000000000000005 R08: 0000000000000001 R09: 0000000000000032
> R10: 00000000207a6000 R11: 0000000000000246 R12: 0000000000401e60
> R13: 0000000000401ef0 R14: 0000000000000000 R15: 0000000000000000
> Code: ff 66 90 55 48 89 e5 41 57 41 56 41 55 41 54 49 89 fd 53 49 89 f4 48
> 83 ec 08 e8 24 49 29 ff 49 8b bd 90 01 00 00 e8 78 fd ff ff <48> 8b 38 48 89
> c3 be 15 11 00 00 e8 e8 7e ff ff 44 8b 73 34 44
> RIP: binder_poll+0x28/0xf0 drivers/android/binder.c:4371 RSP:
> ffffc900017d3df0
> CR2: 0000000000000000

Duplicate of:

#syz dup: general protection fault in binder_poll