RFR: 8297967: Make frame::safe_for_sender safer

[Thomas Stuefe]

On Thu, 1 Dec 2022 18:32:54 GMT, Johannes Bechberger <duke at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/frame_aarch64.cpp line 268:
>> 
>>> 266:   // Will the pc we fetch be non-zero (which we'll find at the oldest frame) and readable
>>> 267: 
>>> 268:   if (!os::is_readable_pointer(this->fp() + return_addr_offset * sizeof(address))) {
>> 
>> Address computation looks wrong: `fp()` returns an `intptr_t*`, so `return_addr_offset` gets scaled automatically before the addition. Wouldn't `thread->is_in_usable_stack(fp())` be a better check?
>
>> Wouldn't thread->is_in_usable_stack(fp()) be a better check?
> 
> No, this would check something different.
> 
>> Address computation looks wrong
> 
> But tests show that it seems to be correct.

I think Martin is right.

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PR: https://git.openjdk.org/jdk/pull/11461