portage-utils: heap-based buffer overflow in qlop.c

Description:
Portage-utils is small and fast portage helper tools written in C.

I discovered that a crafted file is able to cause an heap-based buffer overflow.

The complete ASan output:

~ # qlop -f $CRAFTED_FILE -s
Mon Jan 25 11:38:31 2016 >>> gentoo
=================================================================
==14281==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61900001e44a at pc 0x000000425676 bp 0x7fff2b3f3970 sp 0x7fff2b3f3130
READ of size 1 at 0x61900001e44a thread T0
    #0 0x425675 in __interceptor_strncmp /var/tmp/portage/sys-devel/llvm-3.7.1/work/llvm-3.7.1.src/projects/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:218:3
    #1 0x50d5b1 in show_sync_history /tmp/portage/app-portage/portage-utils-0.60/work/portage-utils-0.60/./qlop.c:350:7
    #2 0x50d5b1 in qlop_main /tmp/portage/app-portage/portage-utils-0.60/work/portage-utils-0.60/./qlop.c:687
    #3 0x4e7f22 in q_main /tmp/portage/app-portage/portage-utils-0.60/work/portage-utils-0.60/./q.c:79:10
    #4 0x4e7afe in main /tmp/portage/app-portage/portage-utils-0.60/work/portage-utils-0.60/main.c:1405:9
    #5 0x7fafd8594854 in __libc_start_main /tmp/portage/sys-libs/glibc-2.21-r1/work/glibc-2.21/csu/libc-start.c:289
    #6 0x4192f8 in _init (/usr/bin/q+0x4192f8)

0x61900001e44a is located 0 bytes to the right of 970-byte region [0x61900001e080,0x61900001e44a)
allocated by thread T0 here:
    #0 0x4a839e in realloc /var/tmp/portage/sys-devel/llvm-3.7.1/work/llvm-3.7.1.src/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:61:3
    #1 0x7fafd85dc95f in getdelim /tmp/portage/sys-libs/glibc-2.21-r1/work/glibc-2.21/libio/iogetdelim.c:106

SUMMARY: AddressSanitizer: heap-buffer-overflow /var/tmp/portage/sys-devel/llvm-3.7.1/work/llvm-3.7.1.src/projects/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:218:3 in __interceptor_strncmp
Shadow bytes around the buggy address:
  0x0c327fffbc30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c327fffbc40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c327fffbc50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c327fffbc60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c327fffbc70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c327fffbc80: 00 00 00 00 00 00 00 00 00[02]fa fa fa fa fa fa
  0x0c327fffbc90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fffbca0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c327fffbcb0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c327fffbcc0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c327fffbcd0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd                                                                                                                                                                                                              
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                                                                                                                                                                                                                                                  
==14281==ABORTING

Affected version:
All versions.

Fixed version:
0.61

Commit fix:
https://gitweb.gentoo.org/proj/portage-utils.git/commit/?id=7aff0263204d80304108dbe4f0061f44ed8f189f

Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.

Timeline:
2016-01-26: bug discovered
2016-01-27: bug reported to upstream
2016-01-29: upstream release a fix
2016-02-16: blog post about the issue

Note:
This bug was found with American Fuzzy Lop.

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portage-utils: heap-based buffer overflow in qlop.c

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