Bus error in zzip_disk_findfirst (src/zzip/mmapped.c) [CVE-2018-6540]

[ProbeFuzzer]

On latest version (0.13.67) and master branch of zziplib:
there is a bus error caused by loading of misaligned address in zzip_disk_findfirst function of src/zzip/mmapped.c, which could be triggered by the POC below. Note that this issue is different from CVE-2018-6484.

The issue happens since the pointer "trailer" (line 420) could be manipulated by a crafted zip file, resulting in a misaligned memory access and bus error. Note that the issue is in libzip and may affect downstream programs.

419             struct zzip_disk_trailer *trailer = (struct zzip_disk_trailer *) p;
420             zzip_size_t rootseek = zzip_disk_trailer_get_rootseek(trailer);

To reproduce the issue, run: ./unzip-mem $POC
The POC could be downloaded at: https://github.com/ProbeFuzzer/poc/blob/master/zziplib/zziplib_0-13-67_unzip-mem_memory-alignment-errors_zzip_disk_findfirst.zip

master/src/zzip/mmapped.c:420:36: runtime error: load of misaligned address 0x7fc6924310f2 for type 'uint32_t', which requires 4 byte alignment
0x7fc6924310f2: note: pointer points here
47 00 00 00 80 00 b5 b5 b5 b5 b5 b5 b5 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^

[abergmann]

CVE-2018-6540 was assigned to this issue.
https://nvd.nist.gov/vuln/detail/CVE-2018-6540

[gdraheim]

can not reproduce in test_65407

[gdraheim]

after double-checking the download-zip, the error is now reproduced in

make test_65402

[gdraheim]

fixed => now OK for test_65402

[gdraheim]

The main problem had been

    if (file->stored + size >= file->endbuf)
    {
        DBG1("try to read beyond end of file");
        return 0; /* ESPIPE */
    }

[gdraheim]

checking back v0.13.67 where the testcase has shown the problem => fixed