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Re: [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189]

From: Florian Weimer <fw at deneb dot enyo dot de>
To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
Cc: libc-alpha at sourceware dot org, "H.J. Lu" <hjl dot tools at gmail dot com>
Date: Tue, 11 Jul 2017 10:42:11 +0200
Subject: Re: [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189]
Authentication-results: sourceware.org; auth=none
References: <20170710200054.GA11938@gmail.com> <alpine.DEB.2.20.1707102014190.13010@digraph.polyomino.org.uk> <CAMe9rOpnbFcCaPo5=E=HtAjiHTQGqEk-xco5R-1y1vik42GMYw@mail.gmail.com> <fb4d2a0f-8588-bf2a-fe4b-0bce0dd03054@linaro.org>

* Adhemerval Zanella:

>> +CFLAGS-tst-ssp-1.c = -Wno-format -Wno-deprecated-declarations -Wno-error \
>> +		     -O0 -fstack-protector
>
> Why explicit -O0 here?

The test case is invalid C because it writes out of bounds, and newer
compiler versions can see that.  I'd suggest to use
-fstack-protector-all and a memory barrier instead (along with
comments).  That should mean that none of the -W flags are necessary,
either.

References:
- [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189]
  - From: H.J. Lu
- Re: [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189]
  - From: Joseph Myers
- Re: [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189]
  - From: H.J. Lu
- Re: [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189]
  - From: Adhemerval Zanella

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