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Re: [PATCH] demangler, only access valid fields for DEMANGLE_COMPONENT_FIXED_TYPE.


On 05/28/2014 09:38 PM, Andrew Burgess wrote:
> In two places when a struct demangle_component is of type
> DEMANGLE_COMPONENT_FIXED_TYPE we fall back to accessing the default
> s_binary member of the union rather than the s_fixed member.  This is
> incorrect and can cause the demangler to crash.
> 
> In d_dump I've changed the code to only access the s_fixed member of the
> union, and also added printing of the remaining parts of the s_fixed
> struct, this felt like the most useful thing to do.
> 
> I've added a new test, this causes a SIGSEGV for me before the patch, and
> is fine afterwords, however, this undefined, so might not cause a crash on
> all platforms.

Hi Andrew,

As you know, I'm not a demangler maintainer, but in any case, I took a look
and this looks good to me.

> diff --git a/libiberty/testsuite/demangle-expected b/libiberty/testsuite/demangle-expected
> index 453f9a3..0e2bb12 100644
> --- a/libiberty/testsuite/demangle-expected
> +++ b/libiberty/testsuite/demangle-expected
> @@ -4343,3 +4343,9 @@ cereal::detail::InputBindingMap<cereal::JSONInputArchive>::Serializers cereal::p
>  --format=gnu-v3
>  _ZNSt9_Any_data9_M_accessIPZ4postISt8functionIFvvEEEvOT_EUlvE_EERS5_v
>  void post<std::function<void ()> >(std::function<void ()>&&)::{lambda()#1}*& std::_Any_data::_M_access<void post<std::function<void ()> >(void post<std::function<void ()> >(std::function<void ()>&&)::{lambda()#1}*&&)::{lambda()#1}*>()
> +# The following input symbol was found during random, it caused a fault

Could you add a single empty # above, to separate the tests?
I find that that makes it much easier to follow the file.
I have no idea why we can't have/handle real empty lines though.

> +# The following input symbol was found during random, it caused a fault

"during random testing?"

> +# within the demangler, it's not a symbol we'd expect in the real world.

Why not?

> +--format=auto --no-params
> +_Z3xxxDFyuVb
> +xxx(unsigned long long _Fract, bool volatile)
> +xxx
-- 
Pedro Alves


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