[Secure-testing-team] Bug#858763: potrace: CVE-2017-7263

[Salvatore Bonaccorso]

Source: potrace
Version: 1.14-1
Severity: important
Tags: security patch upstream

Hi,

the following vulnerability was published for potrace.

CVE-2017-7263[0]:
| The bm_readbody_bmp function in bitmap_io.c in Potrace 1.14 allows
| remote attackers to cause a denial of service (heap-based buffer
| over-read and application crash) or possibly have unspecified other
| impact via a crafted BMP image. NOTE: this vulnerability exists because
| of an incomplete fix for CVE-2016-8698.

Compiling with ASAN shows the issue in 1.14-1:

----cut---------cut---------cut---------cut---------cut---------cut-----
$ ./src/potrace ~/poc/00210-potrace-heapoverflow-bm_readbody_bmp
=================================================================
==915==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000efd0 at pc 0x00000040d3f9 bp 0x7ffec276e270 sp 0x7ffec276e268
READ of size 8 at 0x60200000efd0 thread T0
    #0 0x40d3f8 in bm_readbody_bmp src/bitmap_io.c:754
    #1 0x409c40 in bm_read src/bitmap_io.c:138
    #2 0x407cc6 in process_file src/main.c:1058
    #3 0x408be1 in main src/main.c:1214
    #4 0x7f242778e2b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0)
    #5 0x401c39 in _start (/root/potrace-1.14/src/.libs/potrace+0x401c39)

0x60200000efd1 is located 0 bytes to the right of 1-byte region [0x60200000efd0,0x60200000efd1)
allocated by thread T0 here:
    #0 0x7f2428301ed0 in calloc (/usr/lib/x86_64-linux-gnu/libasan.so.3+0xc1ed0)
    #1 0x409609 in bm_new src/bitmap.h:121
    #2 0x40b86f in bm_readbody_bmp src/bitmap_io.c:574
    #3 0x409c40 in bm_read src/bitmap_io.c:138
    #4 0x407cc6 in process_file src/main.c:1058
    #5 0x408be1 in main src/main.c:1214
    #6 0x7f242778e2b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0)

SUMMARY: AddressSanitizer: heap-buffer-overflow src/bitmap_io.c:754 in bm_readbody_bmp
Shadow bytes around the buggy address:
  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 fa fa fa fa fa fa
  0x0c047fff9dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9dd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9de0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c047fff9df0: fa fa fa fa fa fa fa fa fa fa[01]fa fa fa 04 fa
  0x0c047fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff9e40: 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
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==915==ABORTING
----cut---------cut---------cut---------cut---------cut---------cut-----

If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2017-7263
    https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7263

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore