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From: Reinoud Koornstra <reinoudkoornstra@gmail.com>
To: Xi Ruoyao <xry111@mengyan1223.wang>
Cc: Florian Weimer <fweimer@redhat.com>,
	 Reinoud Koornstra via Gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: Fortify_source and stack-protector-strong
Date: Wed, 2 Mar 2022 12:05:38 -0800	[thread overview]
Message-ID: <CAAA5faE_s_4LWSDcTJxhdNUdD5_ELgWx=pVmJorf57Koesp_xg@mail.gmail.com> (raw)
In-Reply-To: <2a574a7a0dbb4f1ef4472d2a43b029f0ceca9065.camel@mengyan1223.wang>

Hi Xi,

Thanks for your reply.
Then what is the difference between -D_FORTIFY_SOURCE=1 and
-D_FORTIFY_SOURCE=2 exactly?
The resulting binary size doesn't seem to differ much?
Thanks,

Reinoud.


On Wed, Mar 2, 2022, 11:46 AM Xi Ruoyao <xry111@mengyan1223.wang> wrote:

> On Wed, 2022-03-02 at 11:09 -0800, Reinoud Koornstra via Gcc-help wrote:
> > Hi Florian,
> >
> > Thanks very much for your reply.
> > -D_FORTIFY_SOURCE=1 is just during compile time and -D_FORTIFY_SOURCE=2
> > also has runtime checks for variable length?
>
> Both -D_FORTIFY_SOURCE=1 and -D_FORTIFY_SOURCE=2 determine buffer size
> at compile time.  But they are runtime checks: the input size is
> compared with the buffer size at runtime.  They are not a pure compile-
> time checking like -Wstringop-overflow.
>
> -D_FORTIFY_SOURCE=3 supports runtime calculation of variable-length
> buffer, but it needs Glibc >= 2.35 and GCC >= 12.0 (not released yet).
> --
> Xi Ruoyao <xry111@mengyan1223.wang>
> School of Aerospace Science and Technology, Xidian University
>

  reply	other threads:[~2022-03-02 20:05 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-01 23:23 Reinoud Koornstra
2022-03-02 10:22 ` Florian Weimer
2022-03-02 19:09   ` Reinoud Koornstra
2022-03-02 19:46     ` Xi Ruoyao
2022-03-02 20:05       ` Reinoud Koornstra [this message]
2022-03-02 20:23         ` Xi Ruoyao
2022-03-02 20:45           ` Reinoud Koornstra
2022-03-11 19:01             ` Reinoud Koornstra
2022-03-12  8:19               ` Xi Ruoyao
2022-04-19 11:24               ` Florian Weimer

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