[openssl-dev] Question about valgrind error in DH in 1.0.2

[Andy Polyakov]

> Changing the movzwl to movzbl in bn_get_bits5 eliminates the valgrind
> error.  But this isn't a valid fix since bn_get_bits5 no longer returns
> the correct data.  My assembly skills are near nil.  Maybe someone else
> can propose a valid fix. 
> 
> Having said this, this does show the problem appears to be due to the
> movzwl reading past the end of the buffer by a byte.

Correct.

> Given the data
> allocated on the heap is likely surrounded by guard bytes, this is
> likely a benign read outside the buffer.

Correct.

> But it should still be fixed.

Test attached.

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