Re: [Bug-cpio] out-of-bounds write with cpio 2.11

[Pavel Raiskup]

I'm not able to reproduce both on cpio 2.11 and 2.12 on my box.  I just
see something like this:

  cpio: Malformed number0000000
  cpio: warning: skipped 8 bytes of junk
  cpio: Substituting `.' for empty member name
  .
  cpio: premature end of file

Can you post also steps-to-reproduce?

Pavel

On Tuesday 19 of January 2016 13:49:44 Gustavo Grieco wrote:
> 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.