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Date: Thu, 5 Mar 2015 13:45:02 -0500
From: stephen Turner <stephen.n.turner@...il.com>
To: musl@...ts.openwall.com, pcc@...ts.ludd.ltu.se
Subject: Re: segfault in libc.so

This is what i have found so far on the libc.so corruption now also known
to involve libfl.so.2. Im copying both musl (for an update) and pcc however
this appears to be a pcc specific bug and this email is mostly for that
purpose.

> What I know so far is
>
> * the corruption appears to be limited to libc.so only and once a bad
> libc.so is replaced with a glibc/gcc built libc.so everything is fine.
>
I have to correct this statement, i have now found a second corrupted lib
after running a few compiles, libfl.so.2 generated by binutils for the use
of atleast the "ar" program

the error however when ar is reported is said to be in libc.so, knowing
better at this point i "ldd ar" and found that lib and when i "ldd
libfl.so.2" i get the output yylex symbol not found.

> * Libc.a gets smaller when compilled by pcc while libc.so gets bigger.
> Minute as it may be.
> * Everything can be compiled and work dynamic by pcc except libc.so (what
> makes it so differant from libc.a and everything else?)
> * everything on/before pcc 20150101 returns a visible error when compiling
> musl that I dont recall atm but will report tomorrow (back to 20141201
> atleast)
>
the error is
error /usr/libexec/ccom terminated with status 1
recipe for target src/complex/catanf.lo faild
compiler error bad STCALL hidden reg
I attached the strace from this process which failed in musl-libc and per
your suggestion Rich im also looking into the use of gdb now as well. Since
this is a older version of pcc (albiet not by much) I wonder if this STCALL
reg could point to the corruption by pcc?


> * version 20150110 musl compiles (possibly corrupted havent checked) but
> make4.0 breaks, again visibly in jobs.o
> * version 20150120 everything compiled (but libc.so is corrupt) same for
> the latest version.
>
> Your on the pcc list too so im sure you have noticed no response yet. I
> read that one person is away, I didnt pay attention to the name but im
> guessing one of the main programmers.
>
> So I have shown today that its not a musl issue, though I doubted it was
> anyways, no one has reported a corruption issue. But I found these details
> that will hopefully help identify the root issue eventually.
>
> Thanks
> Stephen
>
The errors im finding at this point are 2 and 3 generations deep, I build a
static system with gcc/glibc on debian and move everything to a initrd. I
rebuild in this environment to be a dynamic musl-libc create another initrd
and its with this dynamic initrd building my 3rd gen (or second dynamic) i
get my breakage.

Thanks for your time, I hope to hear back from someone about fixing pcc
soon.

Stephen

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