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Date: Sun, 02 Dec 2018 19:25:56 +0000
From: argante <argante@...me>
To: "musl@...ts.openwall.com" <musl@...ts.openwall.com>
Subject: Re: static linking problem


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, 2 December 2018 19:15, Szabolcs Nagy <nsz@...t> wrote:

> * argante argante@ [2018-12-02 17:20:15 +0000]:
>
> > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> > On Sunday, 2 December 2018 01:18, Rich Felker dalias@ wrote:
> >
> > > On Sat, Dec 01, 2018 at 10:07:53PM +0000, argante wrote:
> > >
> > > > /lib/ld-musl-x86_64.so.1 (0x7ff0dca25000)
> > > > libc.so => /lib/ld-musl-x86_64.so.1 (0x7ff0dca25000)
> > >
> > > This is dynamic-linked, yes. But there's nothing wrong with your
> > > static-linked program. If you really don't want pie, use -no-pie or a
> > > toolchain that wasn't built to produce pie by default (gcc's
> > > --enable-default-pie option at configure time).
>
> > ./configure \
> > CFLAGS="-Os -g0" \
> > CXXFLAGS="${CFLAGS}" \
> > --enable-languages=c,c++ \

> > --enable-default-pie \
>
>        ^^^^^^^^^^^^^^^^^^^^^
>
> > I still can't understand why musl-cross ldd works correctly, and new toolchain shows such a strange result. Did I overlook something? I even tried -Wl,--no-dynamic-linker.
>
> what do you mean strange?
>
> it seems to work exactly as expected.


I checked Alpine, where there is also a default pie. Indeed, ldd behaves the same:

# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-alpine-linux-musl/6.4.0/lto-wrapper
Target: x86_64-alpine-linux-musl
Configured with: /home/buildozer/aports/main/gcc/src/gcc-6.4.0/configure --prefix=/usr
...
--enable-__cxa_atexit --enable-default-pie --enable-cloog-backend --enable-
                      ^^^^^^^^^^^^^^^^^^^^
Thread model: posix
gcc version 6.4.0 (Alpine 6.4.0)

# gcc -static test.c
# ldd a.out
	ldd (0x7f02ef28d000)


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, 2 December 2018 01:18, Rich Felker <dalias@> wrote:

> On Sat, Dec 01, 2018 at 10:07:53PM +0000, argante wrote:

> > ldd a.out
> >
> > ==========
> >
> > ldd (0x7fb6c936f000)
>
> Is this the musl ldd? I believe it will do this or similar, and that's
> a known bug or at least limitation. It should report that the program
> is not dynamic-linked.


yes, this is musl ldd.


but Gentoo:

# gcc -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-gentoo-linux-musl/gcc-bin/7.3.0/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-gentoo-linux-musl/7.3.0/lto-wrapper
Target: x86_64-gentoo-linux-musl
Configured with: /var/tmp/portage/sys-devel/gcc-7.3.0-r3/work/gcc-7.3.0/configure --host=x86_64-gentoo-linux-musl --build=x86_64-gentoo-linux-musl --prefix=/usr

...

--without-isl --disable-libsanitizer --enable-default-pie --enable-default-ssp
                                     ^^^^^^^^^^^^^^^^^^^^
Thread model: posix
gcc version 7.3.0 (Gentoo Hardened 7.3.0-r3 p1.4)


# gcc -static test.c
# ldd a.out
ldd: a.out: Not a valid dynamic program
# ls -l /usr/bin/ldd
lrwxrwxrwx 1 root root 24 Nov 13 21:27 /usr/bin/ldd -> /lib/ld-musl-x86_64.so.1

or:

# gcc -c -fPIE test.c
# gcc -static -pie test.o
# ldd a.out
ldd: a.out: Not a valid dynamic program
# readelf -l a.out

Elf file type is EXEC (Executable file)
Entry point 0x40014d
There are 4 program headers, starting at offset 64

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000000000000 0x0000000000400000 0x0000000000400000
                 0x000000000000133c 0x000000000000133c  R E    0x200000
  LOAD           0x0000000000001fd8 0x0000000000601fd8 0x0000000000601fd8
                 0x0000000000000130 0x0000000000000840  RW     0x200000
  GNU_STACK      0x0000000000000000 0x0000000000000000 0x0000000000000000
                 0x0000000000000000 0x0000000000000000  RW     0x10
  GNU_RELRO      0x0000000000001fd8 0x0000000000601fd8 0x0000000000601fd8
                 0x0000000000000028 0x0000000000000028  R      0x1

 Section to Segment mapping:
  Segment Sections...
   00     .init .text .fini .rodata .eh_frame
   01     .ctors .dtors .data.rel.ro .data .bss
   02
   03     .ctors .dtors .data.rel.ro



that's why it seemed surprising to me.

thx

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