Re: [PATCH net-next v2] bpf: fix verifier NULL pointer dereference

[David Miller]

From: Craig Gallek 
Date: Thu,  2 Nov 2017 11:18:01 -0400

> From: Craig Gallek 
> 
> do_check() can fail early without allocating env->cur_state under
> memory pressure.  Syzkaller found the stack below on the linux-next
> tree because of this.
 ...
> Fixes: 638f5b90d460 ("bpf: reduce verifier memory consumption")
> Fixes: 1969db47f8d0 ("bpf: fix verifier memory leaks")
> Signed-off-by: Craig Gallek 

Applied, thanks Craig.

Re: [PATCH net-next v2] bpf: fix verifier NULL pointer dereference

[Daniel Borkmann]

On 11/02/2017 04:18 PM, Craig Gallek wrote:

From: Craig Gallek 

do_check() can fail early without allocating env->cur_state under
memory pressure.  Syzkaller found the stack below on the linux-next
tree because of this.

   kasan: CONFIG_KASAN_INLINE enabled
   kasan: GPF could be caused by NULL-ptr deref or user memory access
   general protection fault:  [#1] SMP KASAN
   Dumping ftrace buffer:
  (ftrace buffer empty)
   Modules linked in:
   CPU: 1 PID: 27062 Comm: syz-executor5 Not tainted 4.14.0-rc7+ #106
   Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS 
Google 01/01/2011
   task: 8801c2c74700 task.stack: 8801c3e28000
   RIP: 0010:free_verifier_state kernel/bpf/verifier.c:347 [inline]
   RIP: 0010:bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533
   RSP: 0018:8801c3e2f5c8 EFLAGS: 00010202
   RAX: dc00 RBX: fff4 RCX: 
   RDX: 0070 RSI: 817d5aa9 RDI: 0380
   RBP: 8801c3e2f668 R08:  R09: 1100387c5d9f
   R10: 218c4e80 R11: 85b34380 R12: 8801c4dc6a28
   R13:  R14: 8801c4dc6a00 R15: 8801c4dc6a20
   FS:  7f311079b700() GS:8801db30() knlGS:
   CS:  0010 DS:  ES:  CR0: 80050033
   CR2: 004d4a24 CR3: 0001cbcd CR4: 001406e0
   DR0:  DR1:  DR2: 
   DR3:  DR6: fffe0ff0 DR7: 0400
   Call Trace:
bpf_prog_load+0xcbb/0x18e0 kernel/bpf/syscall.c:1166
SYSC_bpf kernel/bpf/syscall.c:1690 [inline]
SyS_bpf+0xae9/0x4620 kernel/bpf/syscall.c:1652
entry_SYSCALL_64_fastpath+0x1f/0xbe
   RIP: 0033:0x452869
   RSP: 002b:7f311079abe8 EFLAGS: 0212 ORIG_RAX: 0141
   RAX: ffda RBX: 00758020 RCX: 00452869
   RDX: 0030 RSI: 20168000 RDI: 0005
   RBP: 7f311079aa20 R08:  R09: 
   R10:  R11: 0212 R12: 004b7550
   R13: 7f311079ab58 R14: 004b7560 R15: 
   Code: df 48 c1 ea 03 80 3c 02 00 0f 85 e6 0b 00 00 4d 8b 6e 20 48 b8 00 00 00 00 
00 fc ff df 49 8d bd 80 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 b6 0b 
00 00 49 8b bd 80 03 00 00 e8 d6 0c 26
   RIP: free_verifier_state kernel/bpf/verifier.c:347 [inline] RSP: 
8801c3e2f5c8
   RIP: bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533 RSP: 8801c3e2f5c8
   ---[ end trace c8d37f339dc64004 ]---

Fixes: 638f5b90d460 ("bpf: reduce verifier memory consumption")
Fixes: 1969db47f8d0 ("bpf: fix verifier memory leaks")
Signed-off-by: Craig Gallek 


Acked-by: Daniel Borkmann 

Re: [PATCH net-next v2] bpf: fix verifier NULL pointer dereference

[Alexei Starovoitov]

On 11/2/17 8:18 AM, Craig Gallek wrote:

From: Craig Gallek 

do_check() can fail early without allocating env->cur_state under
memory pressure.  Syzkaller found the stack below on the linux-next
tree because of this.

  kasan: CONFIG_KASAN_INLINE enabled
  kasan: GPF could be caused by NULL-ptr deref or user memory access
  general protection fault:  [#1] SMP KASAN
  Dumping ftrace buffer:
 (ftrace buffer empty)
  Modules linked in:
  CPU: 1 PID: 27062 Comm: syz-executor5 Not tainted 4.14.0-rc7+ #106
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS 
Google 01/01/2011
  task: 8801c2c74700 task.stack: 8801c3e28000
  RIP: 0010:free_verifier_state kernel/bpf/verifier.c:347 [inline]
  RIP: 0010:bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533
  RSP: 0018:8801c3e2f5c8 EFLAGS: 00010202
  RAX: dc00 RBX: fff4 RCX: 
  RDX: 0070 RSI: 817d5aa9 RDI: 0380
  RBP: 8801c3e2f668 R08:  R09: 1100387c5d9f
  R10: 218c4e80 R11: 85b34380 R12: 8801c4dc6a28
  R13:  R14: 8801c4dc6a00 R15: 8801c4dc6a20
  FS:  7f311079b700() GS:8801db30() knlGS:
  CS:  0010 DS:  ES:  CR0: 80050033
  CR2: 004d4a24 CR3: 0001cbcd CR4: 001406e0
  DR0:  DR1:  DR2: 
  DR3:  DR6: fffe0ff0 DR7: 0400
  Call Trace:
   bpf_prog_load+0xcbb/0x18e0 kernel/bpf/syscall.c:1166
   SYSC_bpf kernel/bpf/syscall.c:1690 [inline]
   SyS_bpf+0xae9/0x4620 kernel/bpf/syscall.c:1652
   entry_SYSCALL_64_fastpath+0x1f/0xbe
  RIP: 0033:0x452869
  RSP: 002b:7f311079abe8 EFLAGS: 0212 ORIG_RAX: 0141
  RAX: ffda RBX: 00758020 RCX: 00452869
  RDX: 0030 RSI: 20168000 RDI: 0005
  RBP: 7f311079aa20 R08:  R09: 
  R10:  R11: 0212 R12: 004b7550
  R13: 7f311079ab58 R14: 004b7560 R15: 
  Code: df 48 c1 ea 03 80 3c 02 00 0f 85 e6 0b 00 00 4d 8b 6e 20 48 b8 00 00 00 00 00 
fc ff df 49 8d bd 80 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 b6 0b 00 
00 49 8b bd 80 03 00 00 e8 d6 0c 26
  RIP: free_verifier_state kernel/bpf/verifier.c:347 [inline] RSP: 
8801c3e2f5c8
  RIP: bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533 RSP: 8801c3e2f5c8
  ---[ end trace c8d37f339dc64004 ]---

Fixes: 638f5b90d460 ("bpf: reduce verifier memory consumption")
Fixes: 1969db47f8d0 ("bpf: fix verifier memory leaks")
Signed-off-by: Craig Gallek 


Acked-by: Alexei Starovoitov 

Thanks!