** Description changed:
system:Ubuntu 16.04.1 LTS
Linux leno 4.4.0-34-generic #53-Ubuntu SMP Wed Jul 27 16:06:39 UTC 2016
x86_64 x86_64 x86_64 GNU/Linux
package in use: libc-bin 2.23-0ubuntu3
The ldd script comes with wired in paths for the 64 bit and 32 bit loaders,
but other architectures
are ignored. On a 64 bit Ubuntu installation, the 32 bit loader is not
present by default, so
32 bit i386 dynamic executables are claimed to be "not a dynamic executable".
This is simply wrong.
On a 64 bit Intel sytem, ldd is frequently used to identify missing necessary
32 bit libraries for
32 bit executables, so their packages may be installed.
It fails to do this unless ld-linux-x32.so.2 is present from the libc6-x32
package.
A minimum fix would be to change the present message to:
- "not a dynamic executable or possibly a missing loader, like
ld-linux-x32.so.2 from the libc6-x32 package."
+ "not a dynamic executable or possibly a missing loader, like
ld-linux-x32.so.2 from the libc6-x32 package."
- A better fix would be to use a program which can handle any architecture ELF
file to report the needed libraries. Default Ubuntu installations do contain
programs like file, readelf, and objdump which can successfully read these ELF
files without loaders being present. The current ldd script even has a
function, noelf, which might be better named "noloader" in which a fallback
report may be issued to identify needed libraries. Using readelf in the
"noloader" function, even different architectures may be correctly identified
and their dependencies output. Below is a sample diff/patch for ldd which
produces useful output for dynamic ELF files
+ A better fix would be to use a program which can handle any architecture ELF
file to report the needed libraries. Default Ubuntu installations do contain
programs like file, readelf, and objdump which can successfully read these ELF
files without loaders being present. The current ldd script even has a
function, noelf, which might be better named "noloader" in which a fallback
report may be issued to identify needed libraries. Using readelf in the
"noloader" function, even different architectures may be correctly identified
and their dependencies output. Below is a sample diff/patch for ldd which
produces useful output for dynamic ELF files
regardless of architecture:
====snip====
97c97
< nonelf ()
---
> noloader ()
99,100c99,105
< # Maybe extra code for non-ELF binaries.
< return 1;
---
> # Extra code for non-native architecture ELF binaries.
> [ "$verbose" == "yes" ] && echo "No loader present for file $1, trying
other options."
> readelf -h $1 1>/dev/null 2>&1
- > if [ $? -eq 0 ]; then
+ > ret=$?
+ > if [ $ret -eq 0 ]; then
> readelf -h $1 | egrep "Class|Type|Machine" && readelf -d $1 | grep
NEEDED
+ > ret=$?
> fi
- > return $?
+ > return $ret
173,174c178,179
< # This can be a non-ELF binary or no binary at all.
< nonelf "$file" || {
---
> # This can be an ELF with no loader present, a non-ELF binary or no
binary at all.
> noloader "$file" || {
====snip===
Comparison of original ldd with updated lddtest on three EFL files of
different
architecture and a text file. The host machine does have the i386 loader
installed, but nothing for ARM.
The files:
$ file x y z txt
x: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically
linked, interpreter /lib/ld-linux.so.3, for GNU/Linux 2.6.14, not stripped
y: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically
linked, interpreter /lib/ld-linux.so.2, for GNU/Linux 2.0.0, not stripped
z: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked,
interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.24,
BuildID[sha1]=41cf4d8c7bbc4d37af0b7a55a7b0c48f8adfb2f5, not stripped
txt: ASCII text
The original ldd output:
$ ldd x y z txt
x:
- not a dynamic executable
+ not a dynamic executable
y:
- linux-gate.so.1 => (0xf777d000)
- libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xf76fe000)
- libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xf7548000)
- /lib/ld-linux.so.2 (0x56633000)
+ linux-gate.so.1 => (0xf777d000)
+ libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xf76fe000)
+ libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xf7548000)
+ /lib/ld-linux.so.2 (0x56633000)
z:
- linux-vdso.so.1 => (0x00007fffc9dac000)
- libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f4f63531000)
- /lib64/ld-linux-x86-64.so.2 (0x0000557d89ab7000)
+ linux-vdso.so.1 => (0x00007fffc9dac000)
+ libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f4f63531000)
+ /lib64/ld-linux-x86-64.so.2 (0x0000557d89ab7000)
txt:
- not a dynamic executable
+ not a dynamic executable
The patched ldd output (with the 386 loader present):
$ ./lddtest x y z txt
x:
- Class: ELF32
- Type: EXEC (Executable file)
- Machine: ARM
- 0x00000001 (NEEDED) Shared library: [libdl.so.2]
- 0x00000001 (NEEDED) Shared library: [libc.so.6]
+ Class: ELF32
+ Type: EXEC (Executable file)
+ Machine: ARM
+ 0x00000001 (NEEDED) Shared library: [libdl.so.2]
+ 0x00000001 (NEEDED) Shared library: [libc.so.6]
y:
- linux-gate.so.1 => (0xf774c000)
- libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xf76cd000)
- libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xf7517000)
- /lib/ld-linux.so.2 (0x56644000)
+ linux-gate.so.1 => (0xf774c000)
+ libm.so.6 => /lib/i386-linux-gnu/libm.so.6 (0xf76cd000)
+ libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xf7517000)
+ /lib/ld-linux.so.2 (0x56644000)
z:
- linux-vdso.so.1 => (0x00007ffe4388a000)
- libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9550131000)
- /lib64/ld-linux-x86-64.so.2 (0x000056018c00d000)
+ linux-vdso.so.1 => (0x00007ffe4388a000)
+ libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9550131000)
+ /lib64/ld-linux-x86-64.so.2 (0x000056018c00d000)
txt:
- not a dynamic executable
+ not a dynamic executable
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https://bugs.launchpad.net/bugs/1616609
Title:
ldd reports incorrectly "not a dynamic executable" when the
executable's loader is not present
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