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Sergio Durigan Junior 69ab5edb4d Don't call "detach_inferior" on "remote_follow_fork" 
This patch fixes a regression that has been introduced by:

  commit bc09b0c14f
  Date:   Fri Jan 19 11:48:11 2018 -0500

      Make linux_nat_detach/thread_db_detach use the inferior parameter

It is possible to trigger this failure with gdb.base/foll-fork.exp (in
which case a bunch of ERROR's will be printed), but one can also use
the test below.

Consider the following example program:

  #include <unistd.h>

  int
  main (int argc, char *argv[])
  {
    fork ();

    return 0;
  }

When running it under gdbserver:

  # ./gdb/gdbserver/gdbserver --multi --once :2345

And debugging it under GDB, we see a segmentation fault:

  # ./gdb/gdb -q -batch -ex 'set remote exec-file ./a.out' -ex 'tar extended-remote :2345' -ex r ./a.out
  Starting program:
  ...
  [Detaching after fork from child process 16102.]
  Segmentation fault (core dumped)

The problem happens on inferior.c:detach_inferior:

  void
  detach_inferior (inferior *inf)
  {
    /* Save the pid, since exit_inferior_1 will reset it.  */
    int pid = inf->pid;
              ^^^^^^^^^

    exit_inferior_1 (inf, 0);

    if (print_inferior_events)
      printf_unfiltered (_("[Inferior %d detached]\n"), pid);
  }

When this code is called from remote.c:remote_follow_fork, the PID is
valid but there is no 'inferior' associated with it, which means that
'inf == NULL'.

The proper fix here is to not call "detach_inferior" when doing remote
follow-fork, because we don't have an inferior to detach on the host
side.

Before bc09b0c1, that call was already a nop (exit_inferior_1 bails
out early if you pass it a NULL inferior), except that it printed
"Inferior PID detached" when "set print inferior-events" is on.  Since
native debugging doesn't call detach_inferior in this case, removing
the call from remote aligns remote debugging output with native
debugging output further.

This has been regtested using BuildBot and no regressions were found.

gdb/ChangeLog:
2018-01-29  Sergio Durigan Junior  <sergiodj@redhat.com>

	* remote.c (remote_follow_fork): Don't call "detach_inferior".
2018-01-29 13:04:51 -05:00
bfd PR22741, objcopy segfault on fuzzed COFF object 2018-01-29 15:50:01 +10:30
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README 

		   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.