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==3506==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x607000007f08 at pc 0x562465fa2eb2 bp 0x7ffd97eaf280 sp 0x7ffd97eaf270
READ of size 4 at 0x607000007f08 thread T0
    #0 0x562465fa2eb1 in PrintFormat::recPrint(OutputString*, void*, void (*)(OutputString*, PrintFormat const*, void*, std::string const&), Node*) const output/formatstring.cc:351
    #1 0x562465fa30f8 in PrintFormat::print(void*, void (*)(OutputString*, PrintFormat const*, void*, std::string const&), Node*, DBHeader const*, VarDbPkg*, PortageSettings const*, SetStability const*, bool) output/formatstring.cc:831
    #2 0x56246602b5cd in PrintFormat::print(void*, void (*)(OutputString*, PrintFormat const*, void*, std::string const&), Node*, DBHeader const*, VarDbPkg*, PortageSettings const*, SetStability const*) output/formatstring.h:460
    #3 0x56246602b5cd in PrintFormat::print(void*, Node*, DBHeader const*, VarDbPkg*, PortageSettings const*, SetStability const*) output/formatstring.h:470
    #4 0x56246602b5cd in print_found_package /var/tmp/portage/app-portage/eix-0.31.5/work/eix-0.31.5/src/eix-diff.cc:262
    #5 0x562466032ab8 in for_each<std::_List_iterator<Package*>, void (*)(Package*)> /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/include/g++-v4/bits/stl_algo.h:3756
    #6 0x562466032ab8 in DiffTrees::diff(PackageTree*, PackageTree*) /var/tmp/portage/app-portage/eix-0.31.5/work/eix-0.31.5/src/eix-diff.cc:203
    #7 0x562466032ab8 in run_eix_diff(int, char**) /var/tmp/portage/app-portage/eix-0.31.5/work/eix-0.31.5/src/eix-diff.cc:424
    #8 0x562465df8d2d in run_program main/main.cc:172
    #9 0x562465df8d2d in main main/main.cc:233
    #10 0x7f7198c2662f in __libc_start_main (/lib64/libc.so.6+0x2062f)
    #11 0x562465df8f58 in _start (/usr/bin/eix+0x56f58)

AddressSanitizer can not describe address in more detail (wild memory access suspected).
SUMMARY: AddressSanitizer: heap-buffer-overflow output/formatstring.cc:351 PrintFormat::recPrint(OutputString*, void*, void (*)(OutputString*, PrintFormat const*, void*, std::string const&), Node*) const
Shadow bytes around the buggy address:
  0x0c0e7fff8f90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff8fa0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff8fb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff8fc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff8fd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c0e7fff8fe0: fa[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff8ff0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff9000: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff9010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff9020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff9030: 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
==3506==ABORTING