Re: [PATCH] dwarf2: Fix dwarf stack fetch array view size mismatch

[Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>]

On 2022-08-19 21:55, Denis Lukianov wrote:
> On Sat, 2022-08-20 at 02:38 +0100, Denis Lukianov wrote:
>>
>> I know nothing about gdb internals, just reading code in the file:
>>
>> copy (value_contents_all (val).slice (subobj_offset, len),
>>                   value_contents_raw (retval));
>>
>> We know val is allocated to be the length of subobj_type.
>> We know retval is allocated to be the length of subobj_type.
>> We know len is the length of subobj_type.
>> We know slice only gives a view same size or smaller.
>>
>> So, the source array_view length must be len - subobj_offset.
>>
>> Therefore source array_view size will be of the length of subobj_type
>> and match the destination only in the event that subobj_offset
>> happens
>> to be zero. The line above does not guarantee it:
>>
>> subobj_offset += n - max;
>>
>> So it looks broken for big endian systems. And maybe any subtype that
>> is not the first element of a type on the others.
>>
> 
> My bad, val is allocated to be length of type.
> 
> So I'm wrong about all this and the code is fine :)
> 

Ok, thanks for digging into it, the more eyes on the code the better.

Simon