Heap-buffer overread in read_pre_biff8_read_name_and_fmla on a fuzzed xls file.

Git versions of glib, goffice, gnumeric, libgsf and libxml2.

Test case: http://jutaky.com/fuzzing/gnumeric_case_2339_346389.xls

==26157== ERROR: AddressSanitizer: heap-buffer-overflow on address 0x600c00096e9e at pc 0x7f81c36fa56c bp 0x7fffbb055000 sp 0x7fffbb054ff8
READ of size 1 at 0x600c00096e9e thread T0
    #0 0x7f81c36fa56b in read_pre_biff8_read_name_and_fmla /gnumeric/plugins/excel/ms-obj.c:644
    #1 0x7f81c36fc886 in ms_obj_read_pre_biff8_obj /gnumeric/plugins/excel/ms-obj.c:757
    #2 0x7f81c3702293 in ms_read_OBJ /gnumeric/plugins/excel/ms-obj.c:1283 (discriminator 2)
    #3 0x7f81c3672199 in excel_read_sheet /gnumeric/plugins/excel/ms-excel-read.c:6663
    #4 0x7f81c367682c in excel_read_BOF /gnumeric/plugins/excel/ms-excel-read.c:6999
    #5 0x7f81c3677eda in excel_read_workbook /gnumeric/plugins/excel/ms-excel-read.c:7089
    #6 0x7f81c35edc8c in excel_enc_file_open /gnumeric/plugins/excel/boot.c:193
    #7 0x7f81c35ee92a in excel_file_open /gnumeric/plugins/excel/boot.c:250
    #8 0x7f81e49e7f1e in go_plugin_loader_module_func_file_open /goffice/goffice/app/go-plugin-loader-module.c:282
    #9 0x7f81e49f0e80 in go_plugin_file_opener_open /goffice/goffice/app/go-plugin-service.c:685 (discriminator 1)
    #10 0x7f81e49fd7cf in go_file_opener_open /goffice/goffice/app/file.c:417
    #11 0x7f81e5b60c50 in workbook_view_new_from_input /gnumeric/src/workbook-view.c:1281
    #12 0x7f81e5b6143f in workbook_view_new_from_uri /gnumeric/src/workbook-view.c:1341
    #13 0x40a6e0 in main /gnumeric/src/main-application.c:322
    #14 0x7f81e02e0bc4 in __libc_start_main ??:?
    #15 0x403de8 in _start ??:?
0x600c00096e9e is located 0 bytes to the right of 62-byte region [0x600c00096e60,0x600c00096e9e)

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Juha Kylmänen
Research Assistant, OUSPG