Headline
CVE-2021-42585: Heap-buffer-overflow in copy_compressed_bytes in decode_r2007.c:332 · Issue #351 · LibreDWG/libredwg
A heap buffer overflow was discovered in copy_compressed_bytes in decode_r2007.c in dwgread before 0.12.4 via a crafted dwg file.
Affected version
the latest commit and 0.12.4
What’s the problem?
A heap buffer overflow was discovered in copy_compressed_bytes in decode_r2007.c:332.
ASAN report:
./dwgread ./tests_64205
ERROR: Section[7]->pages[0] overflow
Warning: Failed to find section_info[1]
ERROR: Failed to read header section
Warning: Failed to find section_info[3]
ERROR: Failed to read class section
Warning: Failed to find section_info[7]
ERROR: Failed to read objects section
Warning: Failed to find section_info[2]
Warning: thumbnail.size mismatch: 185216 != 163880
ERROR: Failed to find page 222
=================================================================
==9485==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000002e3 at pc 0x000000ca5f2b bp 0x7ffdbc6926d0 sp 0x7ffdbc6926c8
WRITE of size 8 at 0x6020000002e3 thread T0
#0 0xca5f2a in memcpy /usr/include/x86_64-linux-gnu/bits/string3.h:53:10
#1 0xca5f2a in copy_compressed_bytes /root/fuzz/libredwg/src/decode_r2007.c:332:7
#2 0xca4195 in decompress_r2007 /root/fuzz/libredwg/src/decode_r2007.c:523:7
#3 0xcaa7fe in read_data_page /root/fuzz/libredwg/src/decode_r2007.c:728:13
#4 0xcaa319 in read_data_section /root/fuzz/libredwg/src/decode_r2007.c:811:19
#5 0xc9be6b in read_2007_section_revhistory /root/fuzz/libredwg/src/decode_r2007.c:1945:11
#6 0xc83d65 in read_r2007_meta_data /root/fuzz/libredwg/src/decode_r2007.c:2387:12
#7 0x4f9fcc in decode_R2007 /root/fuzz/libredwg/src/decode.c:3836:11
#8 0x4e49ab in dwg_decode /root/fuzz/libredwg/src/decode.c:248:29
#9 0x4c75cc in dwg_read_file /root/fuzz/libredwg/src/dwg.c:254:11
#10 0x4c5d47 in main /root/fuzz/libredwg/programs/dwgread.c
#11 0x7f581684583f in __libc_start_main /build/glibc-S7Ft5T/glibc-2.23/csu/../csu/libc-start.c:291
#12 0x41ba58 in _start (/root/fuzz/pocs/dwgread+0x41ba58)
0x6020000002e3 is located 3 bytes to the right of 16-byte region [0x6020000002d0,0x6020000002e0)
allocated by thread T0 here:
#0 0x495a22 in calloc (/root/fuzz/pocs/dwgread+0x495a22)
#1 0xca9e98 in read_data_section /root/fuzz/libredwg/src/decode_r2007.c:774:26
SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/include/x86_64-linux-gnu/bits/string3.h:53:10 in memcpy
Shadow bytes around the buggy address:
0x0c047fff8000: fa fa 00 00 fa fa 00 fa fa fa 00 fa fa fa 00 fa
0x0c047fff8010: fa fa 00 fa fa fa 00 fa fa fa 00 fa fa fa 06 fa
0x0c047fff8020: fa fa 04 fa fa fa 04 fa fa fa 04 fa fa fa 04 fa
0x0c047fff8030: fa fa 04 fa fa fa 00 06 fa fa 04 fa fa fa 04 fa
0x0c047fff8040: fa fa 00 00 fa fa 00 00 fa fa 02 fa fa fa 02 fa
=>0x0c047fff8050: fa fa 02 fa fa fa 02 fa fa fa 00 00[fa]fa fa fa
0x0c047fff8060: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8070: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8080: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8090: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff80a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==9485==ABORTING
Compile command
CC="clang" CFLAGS="-O1 -g -fsanitize=address" ./configure --enable-release --disable-shared && make
How can we reproduce the issue?
unzip tests_64205.zip
dwgread ./tests_64205
POC file :
tests_64205.zip