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License: GNU General Public License v3.0
LibreDWG LibreDWG is a free C library to read and write DWG files. This program is part of the GNU project, released under the aegis of GNU. It is licensed under the terms of the GNU General Public License version 3 (or at you option any later version). DWG is a file format created in the 70's for the emerging CAD applications. Currently it is the native file format of AutoCAD, a proprietary CAD program developed by AutoDesk. LibreDWG is a fork from LibDWG due to its usage of Esperanto, which we think is not the best strategy for a free software project which aims to get lots of contributors. LibreDWG is written in English. Since we forked LibDWG (May 16, 2009), its development seems to have been inactive. At the moment (September 25, 2009) our decoder is almost done. We are reaching 100% read support in our data structures parser but we still need a test suite. Among the example applications we wrote using LibreDWG is an initial SVG conversion tool. Please contact us if you can help. The program dwg_ps (in examples/) reads DWG and outputs Postscript; it depends on pslib: <http://pslib.sourceforge.net>. In many GNU/Linux distributions, this is available by installing the pslib-dev package. If the configure script does not find pslib, dwg_ps will not be built. Sometimes we hang on our IRC channel which is #libredwg at irc.freenode.net If you don't find us there, please email the package maintainers: Felipe Corrêa da Silva Sanches <[email protected]> Rodrigo Rodrigues da Silva <[email protected]> If you are looking for general information about the project, check our website: http://www.gnu.org/software/libredwg == Building and installing the library == You need the following dependencies: - Basic development tools (gcc, autoconf and libtool) - SWIG 1.7+ - TeXinfo - Python development headers (debian: python-dev; yum: python-devel) See INSTALL for generic instructions. Basically, you do: $ ./autogen.sh (if you checked out the source code from git) $ ./configure [options] $ make $ make check # optional but strongly encouraged while LibreDWG is alpha $ make install This builds and installs various files in the "installation dirs": $libdir ($exec_prefix/lib) -- library files (libredwg.*) $includedir ($prefix/include) -- dwg.h $infodir ($datarootdir/info) -- LibreDWG.info Use "./configure --help" to see a full list of options you can use to customize the installation dirs. Other options recognized by configure are: --enable-trace NB: This is an experimental feature that is not in its final form. Enable runtime tracing (default: no). When enabled, the environment variable LIBREDWG_TRACE is consulted on the first decode/encode attempt. Its value is an integer: 0 (no output) through 9 (full verbosity). --enable-write NB: This is an experimental feature that is not in its under construction, so its highly unstable. Enable write support (default: no). When enabled you activate the write support for the dwg format. == Example usage of the library == The examples directory contains some application code that uses our lib: * load_dwg.c -- This is a skeleton code. Look there if you want to have a quickly glance on how to use the library. * dwg_ps.c -- Opens a DWG file and outputs an PostScript file. This code depends on the PSlib library. On Debian-based systems this is usually available as a package named pslib-dev * testSVG.c -- Opens a DWG file and outputs an SVG (Scalable Vector Graphics) file. SVG is a W3C standard for 2d vector graphics. You can open these files on several free software tools. We recomend Inkscape, a free software vector graphics editor. The testSVG.c program will not handle 3d content from DWG since SVG only supports 2-dimensional images. * get_bmp.c -- Extracts the bmp thumbnail of a dwg file when it is available. * rewrite.c -- Load, rewrite and try to re-read a existing dwg file. Just for writing test. Still failing (as in 08/2010) /*****************************************************************************/ /* LibreDWG - free implementation of the DWG file format */ /* */ /* Copyright (C) 2009, 2010 Free Software Foundation, Inc. */ /* */ /* This library is free software, licensed under the terms of the GNU */ /* General Public License as published by the Free Software Foundation, */ /* either version 3 of the License, or (at your option) any later version. */ /* You should have received a copy of the GNU General Public License */ /* along with this program. If not, see <http://www.gnu.org/licenses/>. */ /*****************************************************************************/
If you try to compile the project in a directory with spaces in the name, it fails while running in a "sed" command.
github address
https://github.com/ArchimedesCAD/libredwg
compile the test case in the source
./configure
make
gcc testSVG.c -I../src/ ../src/.libs/libredwg.a -lm -o fuzz_svg
test with poc
./fuzz_svg segment_poc
the gdb output
Program received signal SIGSEGV, Segmentation fault.
[----------------------------------registers-----------------------------------]
RAX: 0x1f5
RBX: 0x0
RCX: 0x1b
RDX: 0x2
RSI: 0x629390 --> 0x4003
RDI: 0x6d1480 --> 0x3000000017
RBP: 0x7fffffffd690 --> 0x7fffffffd6f0 --> 0x7fffffffe240 --> 0x7fffffffe260 --> 0x0
RSP: 0x7fffffffd668 --> 0x40171d (<output_BLOCK_HEADER+227>: mov QWORD PTR [rbp-0x10],rax)
RIP: 0x401e0f (<get_first_owned_object+63>: mov rax,QWORD PTR [rax])
R8 : 0x7fffffff
R9 : 0x414fc0 ("Found null object reference. Could not output an SVG symbol for this BLOCK_HEADER\n")
R10: 0x7ffff7acc6a0 --> 0x0
R11: 0x246
R12: 0x400d90 (<_start>: xor ebp,ebp)
R13: 0x7fffffffe340 --> 0x2
R14: 0x0
R15: 0x0
EFLAGS: 0x10246 (carry PARITY adjust ZERO sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
0x401e00 <get_first_owned_object+48>: repz ret
0x401e02 <get_first_owned_object+50>: nop WORD PTR [rax+rax*1+0x0]
0x401e08 <get_first_owned_object+56>: mov rax,QWORD PTR [rsi+0x98]
=> 0x401e0f <get_first_owned_object+63>: mov rax,QWORD PTR [rax]
0x401e12 <get_first_owned_object+66>: ret
0x401e13: data32 data32 data32 nop WORD PTR cs:[rax+rax*1+0x0]
0x401e20 <get_next_owned_object>: mov rax,QWORD PTR [rdi+0x30]
0x401e24 <get_next_owned_object+4>: mov eax,DWORD PTR [rax]
[------------------------------------stack-------------------------------------]
0000| 0x7fffffffd668 --> 0x40171d (<output_BLOCK_HEADER+227>: mov QWORD PTR [rbp-0x10],rax)
0008| 0x7fffffffd670 --> 0x41519c --> 0x3e736665643c09 ('\t<defs>')
0016| 0x7fffffffd678 --> 0x6295f0 --> 0x6d1480 --> 0x3000000017
0024| 0x7fffffffd680 --> 0x0
0032| 0x7fffffffd688 --> 0x629390 --> 0x4003
0040| 0x7fffffffd690 --> 0x7fffffffd6f0 --> 0x7fffffffe240 --> 0x7fffffffe260 --> 0x0
0048| 0x7fffffffd698 --> 0x401935 (<output_SVG+469>: add DWORD PTR [rbp-0x34],0x1)
0056| 0x7fffffffd6a0 --> 0x40d1a0a52e680c34
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x0000000000401e0f in get_first_owned_object (hdr_obj=0x6d1480, hdr=0x629390) at dwg.c:359
359 return hdr->first_entity->obj;
gdb-peda$ p hdr->first_entity
$1 = (Dwg_Object_Ref *) 0x1f5 # !!!!!! illegal pointer
gdb-peda$ p hdr->first_entity->obj
Cannot access memory at address 0x1f5
gdb-peda$
As you can see, the hdr->first_entity
is now a illegal pointer , and we got crash
Program received signal SIGSEGV, Segmentation fault.
By using asan , I found this is an heap overflow vulnerability
the binary and the poc:
http://hac425.unaux.com/usr/uploads/2018/07/2407654350.zip
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