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Date:   Wed, 23 Feb 2022 21:16:05 -0800
From:   Kees Cook <keescook@chromium.org>
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc:     Thorsten Leemhuis <regressions@leemhuis.info>,
        Anthony Yznaga <anthony.yznaga@oracle.com>,
        matoro_bugzilla_kernel@matoro.tk,
        Andrew Morton <akpm@linux-foundation.org>,
        "regressions@lists.linux.dev" <regressions@lists.linux.dev>,
        linux-ia64@vger.kernel.org,
        Linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: regression: Bug 215601 - gcc segv at startup on ia64
Message-ID: <202202232030.B408F0E895@keescook>
References: <a3edd529-c42d-3b09-135c-7e98a15b150f@leemhuis.info>
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 <03497313-A472-4152-BD28-41C35E4E824E@chromium.org>
 <94c3be49-0262-c613-e5f5-49b536985dde@physik.fu-berlin.de>
 <9A1F30F8-3DE2-4075-B103-81D891773246@chromium.org>
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On Mon, Feb 21, 2022 at 10:57:01PM +0100, John Paul Adrian Glaubitz wrote:
> Hi Kees!
> 
> On 2/21/22 21:58, Kees Cook wrote:
> >> I have applied this patch on top of 038101e6b2cd5c55f888f85db42ea2ad3aecb4b6 and it doesn't
> >> fix the problem for me. Reverting 5f501d555653f8968011a1e65ebb121c8b43c144, however, fixes
> >> the problem.
> >>
> >> FWIW, this problem doesn't just affect GCC but systemd keeps segfaulting with this change as well.
> > 
> > Very weird! Can you attached either of those binaries to bugzilla (or a URL I can fetch it from)? I can try to figure out where it is going weird...
> 
> Here's the initrd of that particular machine:
> 
> > https://people.debian.org/~glaubitz/initrd.img-5.17.0-rc5+
> 
> You should be able to extract the binaries from this initrd image and the "mount" command,
> for example, should be one of the affected binaries.

In dmesg, do you see any of these reports?

                pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
                        task_pid_nr(current), current->comm, (void *)addr);

I don't see anything out of order in the "mount" binary from the above
initrd. What does "readelf -lW" show for the GCC you're seeing failures
on?

-- 
Kees Cook