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

[Eric Biggers]

On Thu, Jan 11, 2018 at 11:48:28AM +0100, Daniel Borkmann wrote:
> Hi Dmitry,
> 
> On 01/11/2018 11:22 AM, Dmitry Vyukov wrote:
> > On Thu, Jan 11, 2018 at 11:17 AM, syzbot
> >  wrote:
> >> Hello,
> >>
> >> syzkaller hit the following crash on
> >> 4147d50978df60f34d444c647dde9e5b34a4315e
> >> git://git.cmpxchg.org/linux-mmots.git/master
> >> compiler: gcc (GCC) 7.1.1 20170620
> >> .config is attached
> >> Raw console output is attached.
> >> Unfortunately, I don't have any reproducer for this bug yet.
> >>
> >>
> >> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >> Reported-by: syzbot+d85bfb332db8f0794...@syzkaller.appspotmail.com
> >> 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.
> >>
> >> netlink: 3 bytes leftover after parsing attributes in process
> >> `syz-executor5'.
> >> ==
> >> BUG: KASAN: use-after-free in __bpf_prog_put+0x5e8/0x640
> >> kernel/bpf/syscall.c:944
> >> netlink: 'syz-executor5': attribute type 5 has an invalid length.
> >> Read of size 8 at addr 8801d3619658 by task syz-executor0/12398
> >>
> >> CPU: 1 PID: 12398 Comm: syz-executor0 Not tainted 4.15.0-rc7-mm1+ #53
> >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> >> Google 01/01/2011
> >> Call Trace:
> >>  __dump_stack lib/dump_stack.c:17 [inline]
> >>  dump_stack+0x194/0x257 lib/dump_stack.c:53
> >>  print_address_description+0x73/0x250 mm/kasan/report.c:256
> >>  kasan_report_error mm/kasan/report.c:354 [inline]
> >>  kasan_report+0x23b/0x360 mm/kasan/report.c:412
> >>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> >>  __bpf_prog_put+0x5e8/0x640 kernel/bpf/syscall.c:944
> >>  bpf_prog_put+0x1a/0x20 kernel/bpf/syscall.c:961
> >>  prog_fd_array_put_ptr+0x15/0x20 kernel/bpf/arraymap.c:446
> >>  fd_array_map_delete_elem+0xc8/0x110 kernel/bpf/arraymap.c:420
> >>  map_delete_elem kernel/bpf/syscall.c:737 [inline]
> >>  SYSC_bpf kernel/bpf/syscall.c:1814 [inline]
> >>  SyS_bpf+0x22ea/0x4400 kernel/bpf/syscall.c:1782
> >>  entry_SYSCALL_64_fastpath+0x29/0xa0
> >> RIP: 0033:0x452ac9
> >> RSP: 002b:7fb70df60c58 EFLAGS: 0212 ORIG_RAX: 0141
> >> RAX: ffda RBX: 0071bea0 RCX: 00452ac9
> >> RDX: 0010 RSI: 20f02ff0 RDI: 0003
> >> RBP: 03aa R08:  R09: 
> >> R10:  R11: 0212 R12: 006f3890
> >> R13:  R14: 7fb70df616d4 R15: 
> >>
> >> Allocated by task 11996:
> >>  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
> >>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
> >>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541
> >>  kmem_cache_zalloc include/linux/slab.h:694 [inline]
> >>  get_empty_filp+0xfb/0x4f0 fs/file_table.c:122
> >>  path_openat+0xed/0x3530 fs/namei.c:3514
> >>  do_filp_open+0x25b/0x3b0 fs/namei.c:3572
> >>  do_sys_open+0x502/0x6d0 fs/open.c:1059
> >>  SYSC_open fs/open.c:1077 [inline]
> >>  SyS_open+0x2d/0x40 fs/open.c:1072
> >>  entry_SYSCALL_64_fastpath+0x29/0xa0
> >>
> >> Freed by task 11994:
> >>  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:3485 [inline]
> >>  kmem_cache_free+0x86/0x2b0 mm/slab.c:3743
> >>  file_free_rcu+0x5c/0x70 fs/file_table.c:49
> >>  __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
> >>  rcu_do_batch kernel/rcu/tree.c:2675 [inline]
> >>  invoke_rcu_callbacks kernel/rcu/tree.c:2934 [inline]
> >>  __rcu_process_callbacks kernel/rcu/tree.c:2901 [inline]
> >>  rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2918
> >>  __do_softirq+0x2d7/0xb85 kernel/softirq.c:285
> >>
> >> The buggy address belongs to the object at 8801d36195c0
> >>  which belongs to the cache filp of size 456
> >> The buggy address is located 152 bytes inside of
> >>  456-byte region [8801d36195c0, 8801d3619788)
> >> The buggy address belongs to the page:
> >> page:ea00074d8640 count:1 mapcount:0 mapping:8801d36190c0 index:0x0
> >> flags: 0x2fffc000100(slab)
> >> raw: 02fffc000100 8801d36190c0  00010006
> >> raw: ea00074c49a0 ea000747a160 8801dae30180 
> >> page dumped because: kasan: bad access detected
> >>
> >> Memory state around the buggy address:
> >>  8801d3619500: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >>  8801d3619580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> >>>
> >>> 8801d3619600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >>
> >>  

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

[Daniel Borkmann]

Hi Dmitry,

On 01/11/2018 11:22 AM, Dmitry Vyukov wrote:
> On Thu, Jan 11, 2018 at 11:17 AM, syzbot
>  wrote:
>> Hello,
>>
>> syzkaller hit the following crash on
>> 4147d50978df60f34d444c647dde9e5b34a4315e
>> git://git.cmpxchg.org/linux-mmots.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>> Unfortunately, I don't have any reproducer for this bug yet.
>>
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+d85bfb332db8f0794...@syzkaller.appspotmail.com
>> 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.
>>
>> netlink: 3 bytes leftover after parsing attributes in process
>> `syz-executor5'.
>> ==
>> BUG: KASAN: use-after-free in __bpf_prog_put+0x5e8/0x640
>> kernel/bpf/syscall.c:944
>> netlink: 'syz-executor5': attribute type 5 has an invalid length.
>> Read of size 8 at addr 8801d3619658 by task syz-executor0/12398
>>
>> CPU: 1 PID: 12398 Comm: syz-executor0 Not tainted 4.15.0-rc7-mm1+ #53
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:17 [inline]
>>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>>  print_address_description+0x73/0x250 mm/kasan/report.c:256
>>  kasan_report_error mm/kasan/report.c:354 [inline]
>>  kasan_report+0x23b/0x360 mm/kasan/report.c:412
>>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
>>  __bpf_prog_put+0x5e8/0x640 kernel/bpf/syscall.c:944
>>  bpf_prog_put+0x1a/0x20 kernel/bpf/syscall.c:961
>>  prog_fd_array_put_ptr+0x15/0x20 kernel/bpf/arraymap.c:446
>>  fd_array_map_delete_elem+0xc8/0x110 kernel/bpf/arraymap.c:420
>>  map_delete_elem kernel/bpf/syscall.c:737 [inline]
>>  SYSC_bpf kernel/bpf/syscall.c:1814 [inline]
>>  SyS_bpf+0x22ea/0x4400 kernel/bpf/syscall.c:1782
>>  entry_SYSCALL_64_fastpath+0x29/0xa0
>> RIP: 0033:0x452ac9
>> RSP: 002b:7fb70df60c58 EFLAGS: 0212 ORIG_RAX: 0141
>> RAX: ffda RBX: 0071bea0 RCX: 00452ac9
>> RDX: 0010 RSI: 20f02ff0 RDI: 0003
>> RBP: 03aa R08:  R09: 
>> R10:  R11: 0212 R12: 006f3890
>> R13:  R14: 7fb70df616d4 R15: 
>>
>> Allocated by task 11996:
>>  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
>>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
>>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541
>>  kmem_cache_zalloc include/linux/slab.h:694 [inline]
>>  get_empty_filp+0xfb/0x4f0 fs/file_table.c:122
>>  path_openat+0xed/0x3530 fs/namei.c:3514
>>  do_filp_open+0x25b/0x3b0 fs/namei.c:3572
>>  do_sys_open+0x502/0x6d0 fs/open.c:1059
>>  SYSC_open fs/open.c:1077 [inline]
>>  SyS_open+0x2d/0x40 fs/open.c:1072
>>  entry_SYSCALL_64_fastpath+0x29/0xa0
>>
>> Freed by task 11994:
>>  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:3485 [inline]
>>  kmem_cache_free+0x86/0x2b0 mm/slab.c:3743
>>  file_free_rcu+0x5c/0x70 fs/file_table.c:49
>>  __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
>>  rcu_do_batch kernel/rcu/tree.c:2675 [inline]
>>  invoke_rcu_callbacks kernel/rcu/tree.c:2934 [inline]
>>  __rcu_process_callbacks kernel/rcu/tree.c:2901 [inline]
>>  rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2918
>>  __do_softirq+0x2d7/0xb85 kernel/softirq.c:285
>>
>> The buggy address belongs to the object at 8801d36195c0
>>  which belongs to the cache filp of size 456
>> The buggy address is located 152 bytes inside of
>>  456-byte region [8801d36195c0, 8801d3619788)
>> The buggy address belongs to the page:
>> page:ea00074d8640 count:1 mapcount:0 mapping:8801d36190c0 index:0x0
>> flags: 0x2fffc000100(slab)
>> raw: 02fffc000100 8801d36190c0  00010006
>> raw: ea00074c49a0 ea000747a160 8801dae30180 
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>>  8801d3619500: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>  8801d3619580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>>>
>>> 8801d3619600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>
>> ^
>>  8801d3619680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  8801d3619700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==
> 
> 
> Is it the same as "general 

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

[Dmitry Vyukov]

On Thu, Jan 11, 2018 at 11:17 AM, syzbot
 wrote:
> Hello,
>
> syzkaller hit the following crash on
> 4147d50978df60f34d444c647dde9e5b34a4315e
> git://git.cmpxchg.org/linux-mmots.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> Unfortunately, I don't have any reproducer for this bug yet.
>
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+d85bfb332db8f0794...@syzkaller.appspotmail.com
> 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.
>
> netlink: 3 bytes leftover after parsing attributes in process
> `syz-executor5'.
> ==
> BUG: KASAN: use-after-free in __bpf_prog_put+0x5e8/0x640
> kernel/bpf/syscall.c:944
> netlink: 'syz-executor5': attribute type 5 has an invalid length.
> Read of size 8 at addr 8801d3619658 by task syz-executor0/12398
>
> CPU: 1 PID: 12398 Comm: syz-executor0 Not tainted 4.15.0-rc7-mm1+ #53
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  print_address_description+0x73/0x250 mm/kasan/report.c:256
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report+0x23b/0x360 mm/kasan/report.c:412
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
>  __bpf_prog_put+0x5e8/0x640 kernel/bpf/syscall.c:944
>  bpf_prog_put+0x1a/0x20 kernel/bpf/syscall.c:961
>  prog_fd_array_put_ptr+0x15/0x20 kernel/bpf/arraymap.c:446
>  fd_array_map_delete_elem+0xc8/0x110 kernel/bpf/arraymap.c:420
>  map_delete_elem kernel/bpf/syscall.c:737 [inline]
>  SYSC_bpf kernel/bpf/syscall.c:1814 [inline]
>  SyS_bpf+0x22ea/0x4400 kernel/bpf/syscall.c:1782
>  entry_SYSCALL_64_fastpath+0x29/0xa0
> RIP: 0033:0x452ac9
> RSP: 002b:7fb70df60c58 EFLAGS: 0212 ORIG_RAX: 0141
> RAX: ffda RBX: 0071bea0 RCX: 00452ac9
> RDX: 0010 RSI: 20f02ff0 RDI: 0003
> RBP: 03aa R08:  R09: 
> R10:  R11: 0212 R12: 006f3890
> R13:  R14: 7fb70df616d4 R15: 
>
> Allocated by task 11996:
>  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
>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541
>  kmem_cache_zalloc include/linux/slab.h:694 [inline]
>  get_empty_filp+0xfb/0x4f0 fs/file_table.c:122
>  path_openat+0xed/0x3530 fs/namei.c:3514
>  do_filp_open+0x25b/0x3b0 fs/namei.c:3572
>  do_sys_open+0x502/0x6d0 fs/open.c:1059
>  SYSC_open fs/open.c:1077 [inline]
>  SyS_open+0x2d/0x40 fs/open.c:1072
>  entry_SYSCALL_64_fastpath+0x29/0xa0
>
> Freed by task 11994:
>  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:3485 [inline]
>  kmem_cache_free+0x86/0x2b0 mm/slab.c:3743
>  file_free_rcu+0x5c/0x70 fs/file_table.c:49
>  __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
>  rcu_do_batch kernel/rcu/tree.c:2675 [inline]
>  invoke_rcu_callbacks kernel/rcu/tree.c:2934 [inline]
>  __rcu_process_callbacks kernel/rcu/tree.c:2901 [inline]
>  rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2918
>  __do_softirq+0x2d7/0xb85 kernel/softirq.c:285
>
> The buggy address belongs to the object at 8801d36195c0
>  which belongs to the cache filp of size 456
> The buggy address is located 152 bytes inside of
>  456-byte region [8801d36195c0, 8801d3619788)
> The buggy address belongs to the page:
> page:ea00074d8640 count:1 mapcount:0 mapping:8801d36190c0 index:0x0
> flags: 0x2fffc000100(slab)
> raw: 02fffc000100 8801d36190c0  00010006
> raw: ea00074c49a0 ea000747a160 8801dae30180 
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  8801d3619500: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  8801d3619580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>>
>> 8801d3619600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
> ^
>  8801d3619680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  8801d3619700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==


Is it the same as "general protection fault in __bpf_prog_put"?
https://groups.google.com/forum/#!topic/syzkaller-bugs/jUsNMmVgms0

The first stack looks similar, but alloc/free stacks looks