Out-of-bounds read on a fuzzed xls file.

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

Test case: http://jutaky.com/fuzzing/gnumeric_case_29042_99585.xls

==5573== ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60340003c23e at pc 0x7fad53156517 bp 0x7fff82599f60 sp 0x7fff82599720
READ of size 8352 at 0x60340003c23e thread T0
    #0 0x7fad53156516 in ?? ??:0
    #1 0x7fad4d54dc36 in g_array_append_vals /glib/glib/garray.c:425
    #2 0x7fad4d54f4dd in g_byte_array_append /glib/glib/garray.c:1669
    #3 0x7fad2fd04b05 in read_pre_biff8_read_text /gnumeric/plugins/excel/ms-obj.c:548
    #4 0x7fad2fd080b9 in ms_obj_read_pre_biff8_obj /gnumeric/plugins/excel/ms-obj.c:746
    #5 0x7fad2fd0dd8f in ms_read_OBJ /gnumeric/plugins/excel/ms-obj.c:1283 (discriminator 2)
    #6 0x7fad2fc7e1d1 in excel_read_sheet /gnumeric/plugins/excel/ms-excel-read.c:6660
    #7 0x7fad2fc82864 in excel_read_BOF /gnumeric/plugins/excel/ms-excel-read.c:6996
    #8 0x7fad2fc83f12 in excel_read_workbook /gnumeric/plugins/excel/ms-excel-read.c:7086
    #9 0x7fad2fbf9c2c in excel_enc_file_open /gnumeric/plugins/excel/boot.c:193
    #10 0x7fad2fbfa8ca in excel_file_open /gnumeric/plugins/excel/boot.c:250
    #11 0x7fad5139200e in go_plugin_loader_module_func_file_open /goffice/goffice/app/go-plugin-loader-module.c:282
    #12 0x7fad5139af70 in go_plugin_file_opener_open /goffice/goffice/app/go-plugin-service.c:685 (discriminator 1)
    #13 0x7fad513a78bf in go_file_opener_open /goffice/goffice/app/file.c:417
    #14 0x7fad524fd684 in workbook_view_new_from_input /gnumeric/src/workbook-view.c:1281
    #15 0x7fad524fde73 in workbook_view_new_from_uri /gnumeric/src/workbook-view.c:1341
    #16 0x40a6e0 in main /gnumeric/src/main-application.c:322
    #17 0x7fad4cc85bc4 in __libc_start_main ??:?
    #18 0x403de8 in _start ??:?
0x60340003c23e is located 446 bytes to the right of 0-byte region [0x60340003c080,0x60340003c080)

--
Juha Kylmänen
Research Assistant, OUSPG