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Andrew Burgess 44e4c7757a gdb: Handle malformed ELF, symbols in non-allocatable sections
I ended up debugging a malformed ELF where a section containing
executable code was not correctly marked as allocatable.  Before
realising the ELF was corrupted I tried to place a breakpoint on a
symbol in the non-allocatable, executable section, and GDB crashed.

Though trying to debug such an ELF clearly isn't going to go well I
would prefer, as far as possible, that any input, no matter how
corrupted, not crash GDB.

The crash occurs when trying to set a breakpoint on the name of a
function from the corrupted section.  GDB converts the symbol to a
symtab_and_line, and looks up a suitable section for this.

The problem is that the section is actually an obj_section, which is
stored in the table within the objfile, and we only initialise this
table for allocatable sections (see add_to_objfile_sections_full in
objfiles.c).  So, if the symbol is in a non-allocatable section then
we end up referencing an uninitialised obj_section.

Later we call get_sal_arch on the symtab_and_line, which calls
get_objfile_arch, which uses the objfile from the uninitialised
obj_section, which will be nullptr, at which point GDB crashes.

The fix I propose here is that when we setup the section references on
msymbols, we should check if the bfd_section being referenced is
allocatable or not.  If it is not then we should set the section
reference back to the default 0 section (see how MSYMBOL_OBJ_SECTION
and SYMBOL_OBJ_SECTION treat the 0 section index).

With this fix in place GDB no longer crashes.  Instead GDB creates the
breakpoint at the non-allocated address, and then fails, with an
error, when it tries to insert the breakpoint.

gdb/ChangeLog:

	* elfread.c (record_minimal_symbol): Set section index to 0 for
	non-allocatable sections.

gdb/testsuite/ChangeLog:

	* gdb.dwarf2/dw2-bad-elf-other.S: New file.
	* gdb.dwarf2/dw2-bad-elf.c: New file.
	* gdb.dwarf2/dw2-bad-elf.exp: New file.

Change-Id: Ie05436ab4c6a71440304d20ee639dfb021223f8b
2020-01-13 23:57:42 +00:00
bfd ubsan: alpha-vma: timeout 2020-01-13 12:12:05 +10:30
binutils Moev declaration of loop variable outside of the loop. 2020-01-13 17:28:41 +00:00
config Add support for debuginfod to the binutils (disable by default, enabled via a configure time option). 2020-01-09 13:19:20 +00:00
contrib
cpu ubsan: fr30: left shift of negative value 2020-01-13 12:12:05 +10:30
elfcpp
etc
gas [gas][aarch64] Turn on SVE when using f32mm or f64mm extensions 2020-01-13 15:31:39 +00:00
gdb gdb: Handle malformed ELF, symbols in non-allocatable sections 2020-01-13 23:57:42 +00:00
gnulib
gold
gprof Add support for the GBZ80, Z180, and eZ80 variants of the Z80 architecure. Add an ELF based target for these as well. 2020-01-02 14:14:59 +00:00
include [ARC][committed] Update ARC cpu list 2020-01-13 11:16:47 +02:00
intl
ld Regen ld BLD-POTFILES.in 2020-01-13 22:45:36 +10:30
libctf Fix libctf ChangeLog date in most recent entry. 2020-01-05 09:53:14 +04:00
libdecnumber
libiberty
opcodes Add an option to objdump's disassembler to generate ascii art diagrams showing the destinations of flow control instructions. 2020-01-13 12:36:55 +00:00
readline
sim
texinfo
zlib
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.gitattributes
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ar-lib
ChangeLog oops - toplevel changelog entry for previous delta. 2020-01-09 13:37:26 +00:00
compile
config-ml.in
config.guess
config.rpath
config.sub
configure Add support for debuginfod to the binutils (disable by default, enabled via a configure time option). 2020-01-09 13:19:20 +00:00
configure.ac Add support for debuginfod to the binutils (disable by default, enabled via a configure time option). 2020-01-09 13:19:20 +00:00
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		   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.