Still confused about PIE/PIC and default build flags

[Richard Shaw]

So I run into this occasionally and it's still not clear to me. In this
specific case I'm trying to build nanomq[1] and I get the following error:

/usr/bin/ld: CMakeFiles/nano_test.dir/test.c.o: relocation R_X86_64_32
against `.rodata' can not be used when making a PIE object; recompile with
-fPIE
/usr/bin/ld: CMakeFiles/nano_test.dir/test_hash.c.o: relocation R_X86_64_32
against `.rodata' can not be used when making a PIE object; recompile with
-fPIE
[ 36%] Building C object
nng/CMakeFiles/nng.dir/src/sp/protocol/reqrep0/rep.c.o
/usr/bin/ld: CMakeFiles/nano_test.dir/test_dbtree.c.o: relocation
R_X86_64_32 against symbol `topic0' can not be used when making a PIE
object; recompile with -fPIE

Any hints are appreciated.

Thanks,
Richard

[1] https://github.com/emqx/nanomq

[John Reiser]

On 6/12/22 Richard Shaw wrote:
> So I run into this occasionally and it's still not clear to me. In this specific case I'm trying to build nanomq[1] and I get the following error:
>
> /usr/bin/ld: CMakeFiles/nano_test.dir/test.c.o: relocation R_X86_64_32 against `.rodata' can not be used when making a PIE object; recompile with -fPIE

Please post a recipe to reproduce those complaints:
the .spec file (or URL), other context for building, etc.

When I build according to README.md at https://github.com/emqx/nanomq
"Building From Source", without Ninja:

git clone https://github.com/emqx/nanomq.git ; cd nanomq
    git submodule update --init --recursive
    mkdir build && cd build
    cmake ..
    make

then I see no complaints from /usr/bin/ld.

The software package itself is low quality.  gcc complains dozens of
serious errors such as:
    nng/src/nng.c:2269:1: warning: control reaches end of non-void function [-Wreturn-type]
    nng/src/sp/protocol/mqtt/nmq_mqtt.c:271:51: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
    nng/src/supplemental/mqtt/mqtt_qos_db.c:620:13: warning: unused variable ‘rv’ [-Wunused-variable]
      620 |         int rv = sqlite3_exec(db, "COMMIT;", 0, 0, 0);

[Richard Shaw]

On Sun, Jun 12, 2022 at 9:23 PM John Reiser  wrote:
> On 6/12/22 Richard Shaw wrote:
> > So I run into this occasionally and it's still not clear to me. In this
>
> specific case I'm trying to build nanomq[1] and I get the following error:
> > /usr/bin/ld: CMakeFiles/nano_test.dir/test.c.o: relocation R_X86_64_32
>
> against `.rodata' can not be used when making a PIE object; recompile with
> -fPIE
>
> Please post a recipe to reproduce those complaints:
> the .spec file (or URL), other context for building, etc.

Sorry, I was hoping it was obvious. I'm only building in locally right now
so I have uploaded it here:
https://hobbes1069.fedorapeople.org/emqx-nanomq.spec
> When I build according to README.md at https://github.com/emqx/nanomq
> "Building From Source", without Ninja:
> git clone https://github.com/emqx/nanomq.git ; cd nanomq
> git submodule update --init --recursive
> mkdir build && cd build
> cmake ..
> make
>
> then I see no complaints from /usr/bin/ld.

Yes, it seems to be an issue when trying to enforce all of Fedora's build
flags.

Full build log here:
https://hobbes1069.fedorapeople.org/build.log
> The software package itself is low quality.  gcc complains dozens of
> serious errors such as:
>     nng/src/nng.c:2269:1: warning: control reaches end of non-void
> function [-Wreturn-type]
>     nng/src/sp/protocol/mqtt/nmq_mqtt.c:271:51: warning: cast to pointer
> from integer of different size [-Wint-to-pointer-cast]
>     nng/src/supplemental/mqtt/mqtt_qos_db.c:620:13: warning: unused
> variable ‘rv’ [-Wunused-variable]
>       620 |         int rv = sqlite3_exec(db, "COMMIT;", 0, 0, 0);

Thanks. I'll make sure that makes it upstream.

Richard

[John Reiser]

On 6/13/22 04:59, Richard Shaw wrote:
> On Sun, Jun 12, 2022 at 9:23 PM John Reiser wrote:
> Please post a recipe to reproduce those complaints:
> the .spec file (or URL), other context for building, etc.
>
>
> Sorry, I was hoping it was obvious. I'm only building in locally right now so I have uploaded it here:
> https://hobbes1069.fedorapeople.org/emqx-nanomq.spec https://hobbes1069.fedorapeople.org/emqx-nanomq.spec

There still are missing pieces.  From that .spec file:
> # Deal with git submodules not in the archive
> # git clone  --recurse-submodules https://github.com/emqx/nanomq.git
> # from extern project subdirs
> # git archive -o ../../../l8w8jwt.tar.gz HEAD
> Source1:        l8w8jwt.tar.gz
> Source2:        nng-fork.tar.gz
>
> Patch0:         nanomq.patch

Where is nanomq.patch ?  And the path ../../../l8w8jwt.tar
points to a directory which is outside of the build environment.

It would be much easier to help, if the _complete_ information was specified.
Present the issue as a bug report, including the build environment (Fedora 36?  Rawhide?  ...)

[Petr Pisar]

V Sun, Jun 12, 2022 at 06:07:01PM -0500, Richard Shaw napsal(a):
> So I run into this occasionally and it's still not clear to me. In this
> specific case I'm trying to build nanomq[1] and I get the following error:
>
> /usr/bin/ld: CMakeFiles/nano_test.dir/test.c.o: relocation R_X86_64_32
> against `.rodata' can not be used when making a PIE object; recompile with
> -fPIE
> /usr/bin/ld: CMakeFiles/nano_test.dir/test_hash.c.o: relocation R_X86_64_32
> against `.rodata' can not be used when making a PIE object; recompile with
> -fPIE
> [ 36%] Building C object
> nng/CMakeFiles/nng.dir/src/sp/protocol/reqrep0/rep.c.o
> /usr/bin/ld: CMakeFiles/nano_test.dir/test_dbtree.c.o: relocation
> R_X86_64_32 against symbol `topic0' can not be used when making a PIE
> object; recompile with -fPIE
>
> Any hints are appreciated.

It looks like you did not pass -fPIE or -fPIC to a compiler, yet you passed
-fPIE to a linker.

Look at CFLAGS and LDFLAGS envariables passed to cmake program.

Run the build in a verbose mode (make VERBOSE=1) to see the actual invocation
of the compiler when compiling rep.c.o and the linker when using that file to
link an executable.

If you try to package the software into Fedora's RPM package, then the PIE
and PIC options are set with GCC "argument script" using options
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 for the compiler and
-specs=/usr/lib/rpm/redhat/redhat-hardened-ld for the linker. You need to
check that they are indeed presented from CMake configuration to invokation of
compiler and linker.

-- Petr

[Richard Shaw]

On Mon, Jun 13, 2022 at 3:45 AM Petr Pisar  wrote:
> V Sun, Jun 12, 2022 at 06:07:01PM -0500, Richard Shaw napsal(a):
> > So I run into this occasionally and it's still not clear to me. In this
> > specific case I'm trying to build nanomq[1] and I get the following
>
> error:
> > /usr/bin/ld: CMakeFiles/nano_test.dir/test.c.o: relocation R_X86_64_32
> > against `.rodata' can not be used when making a PIE object; recompile
>
> with
> > -fPIE
> > /usr/bin/ld: CMakeFiles/nano_test.dir/test_hash.c.o: relocation
>
> R_X86_64_32
> > against `.rodata' can not be used when making a PIE object; recompile
>
> with
> > -fPIE
> > [ 36%] Building C object
> > nng/CMakeFiles/nng.dir/src/sp/protocol/reqrep0/rep.c.o
> > /usr/bin/ld: CMakeFiles/nano_test.dir/test_dbtree.c.o: relocation
> > R_X86_64_32 against symbol `topic0' can not be used when making a PIE
> > object; recompile with -fPIE
> >
> > Any hints are appreciated.
>
> It looks like you did not pass -fPIE or -fPIC to a compiler, yet you passed
> -fPIE to a linker.
>
> Look at CFLAGS and LDFLAGS envariables passed to cmake program.
>
> Run the build in a verbose mode (make VERBOSE=1) to see the actual
> invocation
> of the compiler when compiling rep.c.o and the linker when using that file
> to
> link an executable.
>
> If you try to package the software into Fedora's RPM package, then the PIE
> and PIC options are set with GCC "argument script" using options
> -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 for the compiler and
> -specs=/usr/lib/rpm/redhat/redhat-hardened-ld for the linker. You need to
> check that they are indeed presented from CMake configuration to
> invokation of
> compiler and linker.

Ahh... I do usually skim the logs and it looked like the build flags were
being applied, but not to those specific files. I swear I like CMake for
the most part but they make it very easy to hide stuff like this in obscure
locations.

Thanks,
Richard

[Richard Shaw]

On Mon, Jun 13, 2022 at 7:07 AM Richard Shaw  wrote:
> On Mon, Jun 13, 2022 at 3:45 AM Petr Pisar  wrote:
> > V Sun, Jun 12, 2022 at 06:07:01PM -0500, Richard Shaw napsal(a):
> > > So I run into this occasionally and it's still not clear to me. In this
> > > specific case I'm trying to build nanomq[1] and I get the following
> >
> > error:
> > > /usr/bin/ld: CMakeFiles/nano_test.dir/test.c.o: relocation R_X86_64_32
> > > against `.rodata' can not be used when making a PIE object; recompile
> >
> > with
> > > -fPIE
> > > /usr/bin/ld: CMakeFiles/nano_test.dir/test_hash.c.o: relocation
> >
> > R_X86_64_32
> > > against `.rodata' can not be used when making a PIE object; recompile
> >
> > with
> > > -fPIE
> > > [ 36%] Building C object
> > > nng/CMakeFiles/nng.dir/src/sp/protocol/reqrep0/rep.c.o
> > > /usr/bin/ld: CMakeFiles/nano_test.dir/test_dbtree.c.o: relocation
> > > R_X86_64_32 against symbol `topic0' can not be used when making a PIE
> > > object; recompile with -fPIE
> > >
> > > Any hints are appreciated.
> >
> > It looks like you did not pass -fPIE or -fPIC to a compiler, yet you
> > passed
> > -fPIE to a linker.
> >
> > Look at CFLAGS and LDFLAGS envariables passed to cmake program.
> >
> > Run the build in a verbose mode (make VERBOSE=1) to see the actual
> > invocation
> > of the compiler when compiling rep.c.o and the linker when using that
> > file to
> > link an executable.
> >
> > If you try to package the software into Fedora's RPM package, then the PIE
> > and PIC options are set with GCC "argument script" using options
> > -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 for the compiler and
> > -specs=/usr/lib/rpm/redhat/redhat-hardened-ld for the linker. You need to
> > check that they are indeed presented from CMake configuration to
> > invokation of
> > compiler and linker.
>
> Ahh... I do usually skim the logs and it looked like the build flags were
> being applied, but not to those specific files. I swear I like CMake for
> the most part but they make it very easy to hide stuff like this in obscure
> locations.

I don't see anything in the appropriate CMakeLists.txt that would override
the build flags, I think it's the whole '-S .' issue in Fedora that is
causing some things not to be passed to sub-projects.

Thanks,
Richard