[PATCH v3 0/5] fcntl fortification

[Maxim Kuvyrkov]

> On Jun 20, 2023, at 15:28, Sergey Bugaev <bugaevc@gmail.com> wrote:
> 
> On Tue, Jun 20, 2023 at 12:41 PM Maxim Kuvyrkov
> <maxim.kuvyrkov@linaro.org> wrote:
>> I don't think CPU architecture plays a role here either.  My guess (didn't verify) is that the difference comes from GCC version and its default C standard.
> 
> But the C standard is being explicitly set in these tests (those
> -std=c89 flags), no?
> 
>> In our case we are running CI in latest Ubuntu LTS (22.04 at the moment), which has GCC 11.
>> 
>> What environment did you test this in?
> 
> I have GCC 13.1 and Clang 16.0 targeting {x86_64,i686}-linux-gnu, GCC
> 12.2 targeting i686-gnu, and GCC master targeting x86_64-gnu. I have
> only run the full testsuite on x86_64-linux-gnu (and it does pass,
> including all the check-installed-headers tests); for the other
> variants I've only checked debug/tst-fortify (which also tries to
> compile the header in various configurations) and tried to build
> sample code against the installed headers manually (but have not
> checked different C standards and _XXXX_SOURCE definitions while doing
> that). I have also done some checks on Compiler Explorer, and indeed I
> can reproduce F_DUPFD_CLOEXEC being unavailable with -std=c89 (or any
> non-GNU C, e.g. -std=c11) there -- but that happens when targeting
> x86_64 too.
> 
> ...Having written the above, I went and re-ran the test suite, and
> traced which files GCC opens, and it does not even look at fcntl3.h
> when running check-installed-headers! That explains it, the CI must
> have _FORTIFY_SOURCE set in the CFLAGS for glibc itself, but I don't,
> and Adhemerval probably doesn't either. With _FORTIFY_SOURCE manually
> added, I can reproduce the exact test failure on my setup too.

We don't set _FORTIFY_SOURCE in our CI's glibc build, but, I think, it comes from Ubuntu's GCC, where it may be enabled by default.  Or are you using Ubuntu and not seeing this with default Ubuntu toolchain?

--
Maxim Kuvyrkov
https://www.linaro.org