Re: general protection fault in free_verifier_state (2)

On Mon, Jan 8, 2018 at 2:58 AM, syzbot
[off-list ref] wrote:

Hello,

syzkaller hit the following crash on
895c0dde398510a5b5ded60e5064c11b94bd30ca
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


IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+fa99e24f3c29d269a7d5@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.

RBP: 0000000000000006 R08: 0000000000000002 R09: 00007ffd20003032
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: ffffffffffffffff R14: 656c6c616b7a7973 R15: 0000000000000004
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3468 Comm: syzkaller619543 Not tainted 4.15.0-rc6-next-20180108+
#90
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:free_func_state kernel/bpf/verifier.c:378 [inline]
RIP: 0010:free_verifier_state+0x6d/0x130 kernel/bpf/verifier.c:388
RSP: 0018:ffff8801d48f77b8 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1ffff1003b6384a0
RDX: 0000000000000000 RSI: 0000000000000071 RDI: 0000000000000388
RBP: ffff8801d48f7800 R08: ffff8801db427d00 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801db1c2500
R13: dffffc0000000000 R14: ffff8801db1c2500 R15: ffff8801db1c2500
FS:  000000000254e880(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020386000 CR3: 00000001cb32e002 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 is_state_visited kernel/bpf/verifier.c:4414 [inline]
 do_check+0x2442/0x9760 kernel/bpf/verifier.c:4488
 bpf_check+0x3087/0x5580 kernel/bpf/verifier.c:5483
 bpf_prog_load+0xbb2/0x1260 kernel/bpf/syscall.c:1205
 SYSC_bpf kernel/bpf/syscall.c:1820 [inline]
 SyS_bpf+0x861/0x32e0 kernel/bpf/syscall.c:1782
 entry_SYSCALL_64_fastpath+0x23/0x9a

hmm. my patch with the fix got lost somehow.
Will resend.