Compressed mipsel binaries hang with upx 3.96

[lancethepants]

What's the problem (or question)?

Mipsel binaries compress with upx 3.96 don't execute, and just hang. I've tried both the upx release binaries, and my self compiled binaries, and both give the same behavior. Here is a strace when a program will hang.

root@RT-C0C1C0F68DE0:~# strace ./upx
execve("./upx", ["./upx"], 0x7f899ce0 /* 22 vars */) = 0
open("/proc/self/exe", O_RDONLY)        = 3
mmap(NULL, 423856, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2aaa8000
mmap(0x2aaa8000, 422838, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x2aaa8000
cacheflush(0x2ab0ed78, 0xa38, 0x3)      = 0
mprotect(0x2ab0d000, 10160, PROT_READ|PROT_EXEC) = 0
readlink("/proc/self/exe", "/mmc/upx", 4095) = 8
cacheflush(0x7fdadae0, 0xd4, 0x3)       = 0
mmap(0x400000, 2310144, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x400000
mmap(0x400000, 2180028, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x400000
cacheflush(0x400000, 0xd4, 0x3)         = 0
cacheflush(0x4000d4, 0x2142e8, 0x3)     = 0
mprotect(0x400000, 2180028, PROT_READ|PROT_EXEC) = 0

What should have happened?

Expect regular binary execution

Do you have an idea for a solution?

No

How can we reproduce the issue?

Try running a release upx mipsel binary (which itself is compressed with upx) on a mipsel target, and execution should hang with no output. If you decompress it then it will operate. But any other binary you compress with it will also hang.

Please tell us details about your environment.

• UPX version used (upx --version):

upx 3.96
UCL data compression library 1.03
zlib data compression library 1.2.11
LZMA SDK version 4.43
Copyright (C) 1996-2020 Markus Franz Xaver Johannes Oberhumer
Copyright (C) 1996-2020 Laszlo Molnar
Copyright (C) 2000-2020 John F. Reiser
Copyright (C) 2002-2020 Jens Medoch
Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
Copyright (C) 1999-2006 Igor Pavlov
UPX comes with ABSOLUTELY NO WARRANTY; for details type 'upx -L'.

• Host Operating System and version:

Tomato Firmware running on Linksys E1550 router

root@RT-C0C1C0F68DE0:~# uname -a
Linux RT-C0C1C0F68DE0 2.6.22.19 #2 Wed Dec 31 11:25:40 MST 2014 mips GNU/Linux

• Host CPU architecture:

root@RT-C0C1C0F68DE0:~# cat /proc/cpuinfo
system type             : Broadcom BCM5357 chip rev 1 pkg 8
processor               : 0
cpu model               : MIPS 74K V4.9
BogoMIPS                : 149.91
cpu MHz                 : 300
wait instruction        : no
microsecond timers      : yes
tlb_entries             : 64
extra interrupt vector  : no
hardware watchpoint     : yes
ASEs implemented        : mips16 dsp
shadow register sets    : 1
VCED exceptions         : not available
VCEI exceptions         : not available

unaligned_instructions  : 0

• Target Operating System and version: Same as host
• Target CPU architecture: Same as host

[jreiser]

Please try the tip of devel branch. Commit 4fb1d41 fixes the problem for big-endian (see #342), and should fix it for little-endian, too. If not, then please upload ("Attach files by ...") a specific executable which does not work. Compress the upload using zip, gzip, or .tgz in order to save space on Github.

[lancethepants]

I compiled from the devel branch, and that seems to have fixed it.
thanks!