Hello, An out-of-bounds write in cpio 2.11 was found in the parsing of cpio files (other version are probably affected). Find attached a test case to reproduce it. The ASAN report is here:
=================================================================
==5480==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x60200000edd0 at pc 0x41f187 bp 0x7fffffffdc50 sp 0x7fffffffdc48
WRITE of size 2 at 0x60200000edd0 thread T0
#0 0x41f186 in cpio_safer_name_suffix
/home/g/Codigo/cpio-2.11+dfsg/src/util.c:1392
#1 0x40b3d7 in process_copy_in
/home/g/Codigo/cpio-2.11+dfsg/src/copyin.c:1391
#2 0x416754 in main /home/g/Codigo/cpio-2.11+dfsg/src/main.c:739
#3 0x7ffff6b5eec4 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21ec4)
#4 0x403408 (/home/g/Codigo/cpio-2.11+dfsg/src/cpio+0x403408)
0x60200000edd1 is located 0 bytes to the right of 1-byte region
[0x60200000edd0,0x60200000edd1)
allocated by thread T0 here:
#0 0x7ffff6f567ef in __interceptor_malloc
(/usr/lib/x86_64-linux-gnu/libasan.so.1+0x547ef)
#1 0x440f3e in xmalloc /home/g/Codigo/cpio-2.11+dfsg/gnu/xmalloc.c:47
#2 0x409c74 in read_in_new_ascii
/home/g/Codigo/cpio-2.11+dfsg/src/copyin.c:1166
#3 0x408a26 in read_in_header
/home/g/Codigo/cpio-2.11+dfsg/src/copyin.c:1043
#4 0x40b354 in process_copy_in
/home/g/Codigo/cpio-2.11+dfsg/src/copyin.c:1361
#5 0x416754 in main /home/g/Codigo/cpio-2.11+dfsg/src/main.c:739
#6 0x7ffff6b5eec4 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21ec4)
SUMMARY: AddressSanitizer: heap-buffer-overflow
/home/g/Codigo/cpio-2.11+dfsg/src/util.c:1392 cpio_safer_name_suffix
Shadow bytes around the buggy address:
0x0c047fff9d60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9d90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff9db0: fa fa fa fa fa fa fa fa fa fa[01]fa fa fa 06 fa
0x0c047fff9dc0: fa fa 05 fa fa fa 00 04 fa fa 00 04 fa fa 00 04
0x0c047fff9dd0: fa fa 00 04 fa fa 00 04 fa fa 00 04 fa fa 00 04
0x0c047fff9de0: fa fa 00 04 fa fa 00 04 fa fa 00 04 fa fa 00 04
0x0c047fff9df0: fa fa 00 04 fa fa 00 04 fa fa 00 04 fa fa fd fa
0x0c047fff9e00: 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
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Contiguous container OOB:fc
ASan internal: fe
==5480==ABORTING
This issue was found using QuickFuzz.
Regards,
Gus.
overflow.cpio
Description: CPIO file
