Keith Seitz
58abdf8878
This patch addresses an issue with malformed/fuzzed debug information that was recently reported in gdb/30639. That bug specifically deals with an ASAN issue, but the reproducer provided by the reporter causes a another failure outside of ASAN: $ ./gdb --data-directory data-directory -nx -q UAF_2 Reading symbols from /home/keiths/UAF_2... Fatal signal: Segmentation fault ----- Backtrace ----- 0x59a53a gdb_internal_backtrace_1 ../../src/gdb/bt-utils.c:122 0x59a5dd _Z22gdb_internal_backtracev ../../src/gdb/bt-utils.c:168 0x786380 handle_fatal_signal ../../src/gdb/event-top.c:889 0x7864ec handle_sigsegv ../../src/gdb/event-top.c:962 0x7ff354c5fb6f ??? 0x611f9a process_coff_symbol ../../src/gdb/coffread.c:1556 0x611025 coff_symtab_read ../../src/gdb/coffread.c:1172 0x60f8ff coff_read_minsyms ../../src/gdb/coffread.c:549 0x60fe4b coff_symfile_read ../../src/gdb/coffread.c:698 0xbde0f6 read_symbols ../../src/gdb/symfile.c:772 0xbde7a3 syms_from_objfile_1 ../../src/gdb/symfile.c:966 0xbde867 syms_from_objfile ../../src/gdb/symfile.c:983 0xbded42 symbol_file_add_with_addrs ../../src/gdb/symfile.c:1086 0xbdf083 _Z24symbol_file_add_from_bfdRKN3gdb7ref_ptrI3bfd18gdb_bfd_ref_policyEEPKc10enum_flagsI16symfile_add_flagEPSt6vectorI14other_sectionsSaISC_EES8_I12objfile_flagEP7objfile ../../src/gdb/symfile.c:1166 0xbdf0d2 _Z15symbol_file_addPKc10enum_flagsI16symfile_add_flagEPSt6vectorI14other_sectionsSaIS5_EES1_I12objfile_flagE ../../src/gdb/symfile.c:1179 0xbdf197 symbol_file_add_main_1 ../../src/gdb/symfile.c:1203 0xbdf13e _Z20symbol_file_add_mainPKc10enum_flagsI16symfile_add_flagE ../../src/gdb/symfile.c:1194 0x90f97f symbol_file_add_main_adapter ../../src/gdb/main.c:549 0x90f895 catch_command_errors ../../src/gdb/main.c:518 0x9109b6 captured_main_1 ../../src/gdb/main.c:1203 0x910fc8 captured_main ../../src/gdb/main.c:1310 0x911067 _Z8gdb_mainP18captured_main_args ../../src/gdb/main.c:1339 0x418c71 main ../../src/gdb/gdb.c:39 --------------------- A fatal error internal to GDB has been detected, further debugging is not possible. GDB will now terminate. This is a bug, please report it. For instructions, see: <https://www.gnu.org/software/gdb/bugs/>. Segmentation fault (core dumped) The issue here is that the COFF offset for the fuzzed symbol's name is outside the string table. That is, the offset is greater than the actual string table size. coffread.c:getsymname actually contains a FIXME about this, and that's what I've chosen to address to fix this issue, following what is done in the DWARF reader: $ ./gdb --data-directory data-directory -nx -q UAF_2 Reading symbols from /home/keiths/UAF_2... COFF Error: string table offset (256) outside string table (length 0) (gdb) Unfortunately, I haven't any idea how else to test this patch since COFF is not very common anymore. GCC removed support for it five years ago with GCC 8.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.