From: Xiaoming Ni <nixiaoming@huawei.com>
To: Paul Eggert <eggert@cs.ucla.edu>, <libc-alpha@sourceware.org>,
<glibc-bugs@sourceware.org>, <unassigned@sourceware.org>,
<drepper.fsp@gmail.com>, <roland@gnu.org>, <carlos@redhat.com>,
<adhemerval.zanella@linaro.org>
Cc: <yukeji@huawei.com>, <wangle6@huawei.com>
Subject: Re: [PATCH v2] stdlib: realpath use malloc replace __alloca to reduce stack overflow risks [BZ #26341]
Date: Sat, 8 Aug 2020 16:54:42 +0800 [thread overview]
Message-ID: <27f372e4-ec8d-340e-e12b-83b2cbca1c5b@huawei.com> (raw)
In-Reply-To: <059aea74-2976-c16a-0a6d-fbde2123ac87@cs.ucla.edu>
On 2020/8/8 7:56, Paul Eggert wrote:
> I don't understand why malloc is required here.
>
> Isn't the problem that the buffer is being allocated over and over
> again? And if you fix that bug, the function should allocate only 8 KiB
> via __alloca on GNU/Linux. Something like the attached (untested) patch,
> say. So why not keep using the stack? That would be more efficient than
> resorting to the heap.
To avoid possible stack overflow risks (the remaining stack space is
uncertain when realpath is called), should we sacrifice some efficiency
and reduce the stack space usage? Use malloc instead of alloca (4k+4k).
thanks
next prev parent reply other threads:[~2020-08-08 8:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-07 10:16 Xiaoming Ni
2020-08-07 19:43 ` Adhemerval Zanella
2020-08-08 0:00 ` Paul Eggert
2020-08-08 9:14 ` Xiaoming Ni
2020-08-07 23:56 ` Paul Eggert
2020-08-08 8:54 ` Xiaoming Ni [this message]
2020-08-09 8:44 ` Paul Eggert
2020-08-09 12:38 ` Florian Weimer
2020-08-09 17:22 ` Paul Eggert
2020-08-10 13:40 ` Adhemerval Zanella
2020-08-11 9:54 ` Paul Eggert
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