On 15.05.20 15:02, Mircea Ciocan wrote:
On 15.05.20 09:46, Michael Olbrich wrote:
On Thu, May 14, 2020 at 03:36:44PM +0200, Mircea Ciocan wrote:
Hello list,
I have the most strange error with the ptxdist-2020.05.0 while
trying to
compile a simple image for the iMX6ULL EVK, the shell segfaults !!!
Here are some information, that you could find useful:
Distribution: Ubuntu 18.04 LTS, 8GB RAM, current updates.
System shell set to bash.
The compilation of everything goes perfectly OK, but while building
the root
filesystem image it crashes, always in the same place (100%
reproducible),
when adding the net-dns-perl package, with the following message;
info: selected ptxconfig:
'configs/platform-mcimx6ull-evk/ptxconfig.tiny'
ptxdist: warning: No dev packages found in
'Firmware/packages-MCIMX6ULL-EVK'
...[snip]...
[compilation goes OK]
----------------
target: root.tgz
----------------
...[snip]...
Configuring readline.
Configuring net-dns-perl.
environment: line 1: 31523 Done { echo "cd
'${work_dir}'
|| exit"; ptxd_dopermissions "${ptxd_reply_perm_files[@]}"; echo ":"; }
31524 Segmentation fault (core dumped) | sh
./Software/ptxdist-2020.05.0/rules/image-root-tgz.make:29: recipe
for target
'./Software/Firmware/platform-MCIMX6ULL-EVK/images/root.tgz' failed
make: ***
[./Software/Firmware/platform-MCIMX6ULL-EVK/images/root.tgz] Error
139
In the system log I get something like:
"vmunix: [132753.581596] sh[10747]: segfault at 7ffe5bdf1fe8 ip
00007fdb0b04930e sp 00007ffe5bdf1fe0 error 6 in
libc-2.27.so[7fdb0afb5000+1e7000]"
I have to say that I rarely, if ever, see this type of crash, and
the build
finishes OK with ptxdist-2020.02.0. Any pointer on how can I fix or
debug
this are greatly appreciated.
Huh, I've never seen anything like this. Some things to test.
Take a look at scripts/lib/ptxd_make_image_prepare_work_dir.sh in
PTXdist.
The relevant code is there. Line 50ff.
If you change line 56 to something like this:
} | tee /tmp/ptxdist-sh-test.txt | sh &&
Then this will save the exact code that the shell executes when it
crashed.
Maybe we can find some clues there. But It's probably a bug in 'sh'.
What's your /bin/sh anyways? For me it's a link to 'dash' but sometimes
it's a bash. You could explicitly try the other here instead of 'sh'
to see
if that crashes as well.
Michael
Hello Michael and thanks for the hint, first things first, the shell
is the GNU bash, I've change it via the update-alternatives, because
more than one time I've had issues with scripts that call /bin/sh, but
assume that is bash.
The logging tap collected the following file:
"cd
'./Software/Firmware/platform-MCIMX6ULL-EVK/build-target/image-root-tgz'
|| exit
chmod 0755 './' &&
chown 0.0 './' &&
chmod 0755 './usr' &&
chown 0.0 './usr' &&
chmod 0755 './usr/sbin' &&
chown 0.0 './usr/sbin' &&
...
!!! Another >>>71940<<< similar lines !!!
...
chmod 0755 './usr/bin/cpuburn-a9' &&
chown 0.0 './usr/bin/cpuburn-a9' &&
:"
Is this just a "cool way" to execute a quatrillion of commands, by
exploiting to the limit the AND_IF (&&) construct to exit on error, or
there is a deeper purpose ?
I could see that some other cool programmer tried some optimization
somewhere in bash and these two worlds collided hard, now that full
Perl and Python packages adds a few tens of thousands of files to the
image that need their permissions fixed.
I'll have a look if there was another way to do it (how was it done in
2020.03.0 and lower, could it be that only two lines have been used
like: chmod -R * && chown -R 0.0 * und fertig ;) ?!?) and see if I
could reproduce it, to make an Ubuntu bug report.
Other ideas and solutions are most welcome.
Thanks for your help,
Mircea
OK, latest update, is definitly a (Ubuntu) bash bug, I've run the
mega-list of commands with bash and dash, bash crashes immediately, dash
takes a mounstrously large amount of time (almost 5min on a beefy
machine with fast SSD), so it is clear why Michael did't see the bug.
A bit of stracing show something like a lot of threads dieing, so
probably bash tries to execute this in parallel and hits something, just
FYI here the last words of bash run strace:
read(255, "mod 0755\t'./usr' &&\nchown 0.0\t'."..., 8192) = 8192
brk(0x56519329b000) = 0x56519329b000
read(255, "tch_map' &&\nchmod 0755\t'./' &&\nc"..., 8192) = 2374
brk(0x5651932bc000) = 0x5651932bc000
brk(0x5651932dd000) = 0x5651932dd000
.... maaaany more similar lines, with different addresses ....
brk(0x565193805000) = 0x565193805000
brk(0x565193826000) = 0x565193826000
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR,
si_addr=0x7ffef981df98} ---
+++ killed by SIGSEGV (core dumped) +++
Segmentation fault (core dumped)
So because switching back to dash here it's a bit difficult, is there
any way that this function could be made a bit more bash-friendly ?
I could gladly test your patches and ideas (vanilla Ubuntu 18.04, with
bash as system shell, is not such a seldom encountered configuration),
but I'm afraid that I'm not in the deep of the PTXdist internals to
start hacking and don't produce conequences.
Best regards,
Mircea
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