Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > linux.kernel > #1571559

Re: keys: GPF in request_key

From David Howells <dhowells@redhat.com>
Newsgroups linux.kernel
Subject Re: keys: GPF in request_key
Date 2017-02-01 14:30 +0100
Message-ID <t6390-6uR-19@gated-at.bofh.it> (permalink)
References <t62cW-5Vf-33@gated-at.bofh.it>
Organization Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

Show all headers | View raw


Dmitry Vyukov <dvyukov@google.com> wrote:

> The line causes the crash is:
>     BUG_ON(index_key->desc_len == 0);
> 
> The addresses that the line tried to access are:
>
> RDI: ffffffffca29fa68
> RDI: ffffffffd7236a28
> RDI: 000000007d19ed68

These are all calculated from R12:

	lea    0x10(%r12),%rdi
	...
	mov    %rdi,%rdx
	shr    $0x3,%rdx
	cmpb   $0x0,(%rdx,%rax,1)

R12 would appear to be index_key - which would correlate with 0x10 being the
offset of desc_len therein - but why muck around with the pointer rather than
just 

In my compiler output,

	BUG_ON(index_key->desc_len == 0);

is turned into:

   0xffffffff8131f023 <+0>:     cmpq   $0x0,0x10(%rsi)
   0xffffffff8131f028 <+5>:     jne    0xffffffff8131f02c <__key_link_begin+9>
   0xffffffff8131f02a <+7>:     ud2    

What compiler are you using?

David

Back to linux.kernel | Previous | NextPrevious in thread | Next in thread | Find similar | Unroll thread


Thread

keys: GPF in request_key Dmitry Vyukov <dvyukov@google.com> - 2017-02-01 13:30 +0100
  Re: keys: GPF in request_key David Howells <dhowells@redhat.com> - 2017-02-01 14:20 +0100
    Re: keys: GPF in request_key Dmitry Vyukov <dvyukov@google.com> - 2017-02-01 14:30 +0100
  Re: keys: GPF in request_key David Howells <dhowells@redhat.com> - 2017-02-01 14:30 +0100
  Re: keys: GPF in request_key David Howells <dhowells@redhat.com> - 2017-02-01 14:50 +0100
    Re: keys: GPF in request_key Dmitry Vyukov <dvyukov@google.com> - 2017-02-01 15:10 +0100
      Re: keys: GPF in request_key David Howells <dhowells@redhat.com> - 2017-02-01 16:00 +0100
        Re: keys: GPF in request_key Dmitry Vyukov <dvyukov@google.com> - 2017-02-01 16:30 +0100
          Re: keys: GPF in request_key David Howells <dhowells@redhat.com> - 2017-02-01 16:50 +0100
            Re: keys: GPF in request_key Dmitry Vyukov <dvyukov@google.com> - 2017-02-01 17:00 +0100
              Re: keys: GPF in request_key David Howells <dhowells@redhat.com> - 2017-02-01 18:00 +0100
                Re: keys: GPF in request_key Dmitry Vyukov <dvyukov@google.com> - 2017-02-01 18:20 +0100

csiph-web