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SubjectRe: keys: GPF in request_key
Date
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

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