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From: Florian Weimer <fweimer@redhat.com>
To: musl@lists.openwall.com
Subject: Re: [PATCH] Fix the use of sigaltstack to return to the saved main stack.
Date: Fri, 12 Jul 2019 11:18:49 +0200	[thread overview]
Message-ID: <87h87r391i.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <20190710212319.GM21055@port70.net> (Szabolcs Nagy's message of "Wed, 10 Jul 2019 23:23:19 +0200")

* Szabolcs Nagy:

> the comment does not make sense to me, the check is obviously
> not redundant.
>
> MINSIGSTKSZ is a libc api, has nothing to do with the kernel
>
> the kernel also defines a MINSIGSZTKSZ but musl is an
> abstraction layer higher, the linux limit should not be
> observable to users, only the limit defined by musl,
> which ensures not only that the kernel can deliver a
> signal but also reserves space of any current or future
> hackery the c runtime may need to do around signal handling,
> so that trivial c language signal handler is guaranteed
> to work.

Please keep in mind that the kernel stack requirements for delivering a
signal vary and tend to increase over time, with newer CPU generations
with larger register files.  It leads to bugs to pretend this value is
constant.

Thanks,
Florian


  parent reply	other threads:[~2019-07-12  9:18 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-09 19:01 James Y Knight
2019-07-09 19:30 ` Rich Felker
2019-07-10 18:04   ` James Y Knight
2019-07-10 18:39     ` Rich Felker
2019-07-10 20:11       ` James Y Knight
2019-07-10 21:23         ` Szabolcs Nagy
2019-07-10 21:48           ` Rich Felker
2019-07-11 15:51             ` James Y Knight
2019-07-12  9:18           ` Florian Weimer [this message]
2019-07-12 16:06             ` Rich Felker

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