Re: KASAN: use-after-free Read in binder_release_work

[Eric Biggers]

On Tue, Apr 03, 2018 at 08:02:02PM -0700, syzbot wrote:
> Hello,
> 
> syzbot hit the following crash on upstream commit
> f2d285669aae656dfeafa0bf25e86bbbc5d22329 (Tue Apr 3 17:45:39 2018 +0000)
> Merge tag 'pm-4.17-rc1' of
> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=0cf1f1aa154f56ff2e8d
> 
> So far this crash happened 4 times on upstream.
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=4827186146050048
> syzkaller reproducer:
> https://syzkaller.appspot.com/x/repro.syz?id=6025869373997056
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=4772918563176448
> Kernel config: https://syzkaller.appspot.com/x/.config?id=686016073509112605
> compiler: gcc (GCC) 7.1.1 20170620
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0cf1f1aa154f56ff2e8d@xxxxxxxxxxxxxxxxxxxxxxxxx
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.
> 
> binder: 4616:4618 transaction failed 29189/-3, size 0-0 line 2963
> binder: release 4616:4618 transaction 114 in, still active
> binder: send failed reply for transaction 114 to 4616:4618
> binder: 4620:4621 ioctl 400448c8 20000200 returned -22
> ==================================================================
> BUG: KASAN: use-after-free in __list_del_entry_valid+0x144/0x150
> lib/list_debug.c:54
> Read of size 8 at addr ffff8801d39a4210 by task kworker/1:2/1891
> 
> CPU: 1 PID: 1891 Comm: kworker/1:2 Not tainted 4.16.0+ #378
> binder: release 4620:4621 transaction 118 out, still active
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: events binder_deferred_func
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x1a7/0x27d lib/dump_stack.c:53
> binder: release 4620:4621 transaction 117 in, still active
>  print_address_description+0x73/0x250 mm/kasan/report.c:256
> binder: undelivered TRANSACTION_COMPLETE
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report+0x23c/0x360 mm/kasan/report.c:412
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> binder: BINDER_SET_CONTEXT_MGR already set
>  __list_del_entry_valid+0x144/0x150 lib/list_debug.c:54
> binder: 4620:4622 ioctl 40046207 0 returned -16
>  __list_del_entry include/linux/list.h:117 [inline]
>  list_del_init include/linux/list.h:159 [inline]
>  binder_dequeue_work_head_ilocked drivers/android/binder.c:893 [inline]
>  binder_dequeue_work_head drivers/android/binder.c:913 [inline]
>  binder_release_work+0x163/0x4b0 drivers/android/binder.c:4191
> binder: 4620:4621 ioctl c0306201 20004000 returned -14
> binder: 4620:4621 ioctl 400448c8 20000200 returned -22
>  binder_thread_release+0x4e1/0x730 drivers/android/binder.c:4396
> binder_alloc: binder_alloc_mmap_handler: 4620 2000c000-2000e000 already
> mapped failed -16
>  binder_deferred_release drivers/android/binder.c:4939 [inline]
>  binder_deferred_func+0x4f4/0x1350 drivers/android/binder.c:5022
> binder_alloc: 4620: binder_alloc_buf, no vma
> binder: 4620:4623 transaction failed 29189/-3, size 0-0 line 2963
>  process_one_work+0xc97/0x1c40 kernel/workqueue.c:2113
> binder_alloc: 4620: binder_alloc_buf, no vma
> binder: 4620:4621 transaction failed 29189/-3, size 0-0 line 2963
> binder: release 4620:4622 transaction 118 in, still active
> binder: release 4620:4622 transaction 117 out, still active
>  worker_thread+0x1c3/0x1380 kernel/workqueue.c:2247
> binder: send failed reply for transaction 118, target dead
> binder: send failed reply for transaction 117, target dead
> binder: BINDER_SET_CONTEXT_MGR already set
> binder: 4624:4625 ioctl 40046207 0 returned -16
>  kthread+0x33c/0x400 kernel/kthread.c:238
> binder: 4624:4625 ioctl 400448c8 20000200 returned -22
>  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
> 
> binder_alloc: 4620: binder_alloc_buf, no vma
> Allocated by task 4618:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
> binder: 4624:4626 transaction failed 29189/-3, size 0-0 line 2963
>  kmem_cache_alloc_trace+0x136/0x740 mm/slab.c:3608
>  kmalloc include/linux/slab.h:512 [inline]
>  kzalloc include/linux/slab.h:701 [inline]
>  binder_transaction+0x13d2/0x8200 drivers/android/binder.c:2900
>  binder_thread_write+0xcf1/0x38b0 drivers/android/binder.c:3513
>  binder_ioctl_write_read.isra.39+0x261/0xcb0 drivers/android/binder.c:4451
>  binder_ioctl+0xb72/0x1417 drivers/android/binder.c:4591
> binder: undelivered TRANSACTION_ERROR: 29189
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>  ksys_ioctl+0x94/0xb0 fs/ioctl.c:701
>  SYSC_ioctl fs/ioctl.c:708 [inline]
>  SyS_ioctl+0x24/0x30 fs/ioctl.c:706
>  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>  entry_SYSCALL_64_after_hwframe+0x42/0xb7
> binder: 4624:4626 ioctl c0306201 20004000 returned -14
> 
> Freed by task 1891:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
>  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
>  __cache_free mm/slab.c:3486 [inline]
>  kfree+0xd9/0x260 mm/slab.c:3801
> binder: BINDER_SET_CONTEXT_MGR already set
>  binder_free_transaction+0x6a/0xa0 drivers/android/binder.c:1966
>  binder_send_failed_reply+0x1c9/0x380 drivers/android/binder.c:2005
>  binder_thread_release+0x4cc/0x730 drivers/android/binder.c:4395
>  binder_deferred_release drivers/android/binder.c:4939 [inline]
>  binder_deferred_func+0x4f4/0x1350 drivers/android/binder.c:5022
>  process_one_work+0xc97/0x1c40 kernel/workqueue.c:2113
>  worker_thread+0x1c3/0x1380 kernel/workqueue.c:2247
>  kthread+0x33c/0x400 kernel/kthread.c:238
> binder: 4624:4627 ioctl 40046207 0 returned -16
>  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
> 
> The buggy address belongs to the object at ffff8801d39a4200
>  which belongs to the cache kmalloc-192 of size 192
> The buggy address is located 16 bytes inside of
>  192-byte region [ffff8801d39a4200, ffff8801d39a42c0)
> The buggy address belongs to the page:
> page:ffffea00074e6900 count:1 mapcount:0 mapping:ffff8801d39a4000 index:0x0
> binder: 4624:4626 ioctl 400448c8 20000200 returned -22
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffff8801d39a4000 0000000000000000 0000000100000010
> raw: ffffea000738fbe0 ffffea00074e6a60 ffff8801dac00040 0000000000000000
> page dumped because: kasan: bad access detected
> 
> binder_alloc: binder_alloc_mmap_handler: 4624 2000c000-2000e000 already
> mapped failed -16
> Memory state around the buggy address:
>  ffff8801d39a4100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8801d39a4180: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
> > ffff8801d39a4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                          ^
>  ffff8801d39a4280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> binder_alloc: 4620: binder_alloc_buf, no vma
>  ffff8801d39a4300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==================================================================
> 
> 
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
> 
> syzbot will keep track of this bug report.
> If you forgot to add the Reported-by tag, once the fix for this bug is
> merged
> into any tree, please reply to this email with:
> #syz fix: exact-commit-title

Martijn, this is going to be fixed by
https://patchwork.kernel.org/patch/10312345/
("ANDROID: binder: prevent transactions into own process"), right?
The syzbot bug ID in that patch is for a bug that is already closed,
so if it's not too late you should use this one.

- Eric