Re: [PATCH 2/2] rseq: Kill process when unknown flags are encountered in ABI structures

Ingo Molnar
2022-08-01T19:40:57Z

* Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> The projects I know about that use rseq at the moment don't rely on the
> old ABI ignoring unset flags:
>
> - glibc initialize the rseq_abi()->flags to 0 and do not use rseq_abi()->rseq_cs->flags yet.
> - tcmalloc initialize rseq_abi()->flags and rseq_abi()->rseq_cs->flags to 0.
> - librseq (still only a master branch, no officially released public API yet) initialize
> rseq_abi()->flags and rseq_abi()->rseq_cs->cs_flags to 0.
> - the Linux kernel selftests initialize rseq_abi()->flags and rseq_abi()->rseq_cs->cs_flags
> to 0.
> - AFAIK DynamoRIO does not rely on the kernel ignoring unset flags bits.
> - AFAIK CRIU does not rely on the kernel ignoring unset flags bits.

Thanks - that's exhaustive enough.

> If anyone else rely on rseq ignoring those unset flags, please yell now.

Well, people are unlikely to see random lkml mails - but if gets reported
as a regression then we need to revert. But I don't expect it to happen.

Thanks,

Ingo