breakpoints/19546: Fix crash after updating breakpoints

One of the last checks update_breakpoints_after_exec does while looping
over the list of breakpoints is check that the breakpoint has a valid
location spec. It uses event_location_empty_p to check if the location spec
is "empty", and if it is, the breakpoint is deleted.

momentary_breakpoint types rely on setting the breakpoint structure's
location spec to NULL, thereby causing an update to delete the breakpoint.
However, event_location_empty_p assumed that locations were never NULL.
As a result, GDB would crash dereferencing a NULL pointer whenever
update_breakpoints_after_exec would encounter a momentary_breakpoint.

This patch creates a new wrapper/helper function which tests that the given
breakpoint's location spec is non-NULL and if it is not "empty"
or "unspecified."

gdb/ChangeLog

	PR breakpoints/19546
	* breakpoint.c (breakpoint_event_location_empty_p): New function.
	(update_breakpoints_after_exec, bkpt_re_set): Use this new function
	instead of event_location_empty_p.

gdb/testsuite/ChangeLog

	PR breakpoints/19546
	* gdb.base/infcall-exec.c: New file.
	* gdb.base/infcall-exec2.c: New file.
	* gdb.base/infcall-exec.exp: New file.
This commit is contained in:
Keith Seitz 2016-02-08 12:57:22 -08:00
parent 224c1b2068
commit 9ef9e6a6a0
6 changed files with 122 additions and 2 deletions

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@ -1,3 +1,10 @@
2016-02-09 Keith Seitz <keiths@redhat.com>
PR breakpoints/19546
* breakpoint.c (breakpoint_event_location_empty_p): New function.
(update_breakpoints_after_exec, bkpt_re_set): Use this new function
instead of event_location_empty_p.
2016-02-09 Keith Seitz <keiths@redhat.com>
* mi/mi-cmd-break.c (mi_cmd_break_insert_1): Use

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@ -3764,6 +3764,14 @@ create_exception_master_breakpoint (void)
}
}
/* Does B have a location spec? */
static int
breakpoint_event_location_empty_p (const struct breakpoint *b)
{
return b->location != NULL && event_location_empty_p (b->location);
}
void
update_breakpoints_after_exec (void)
{
@ -3878,7 +3886,7 @@ update_breakpoints_after_exec (void)
/* Without a symbolic address, we have little hope of the
pre-exec() address meaning the same thing in the post-exec()
a.out. */
if (event_location_empty_p (b->location))
if (breakpoint_event_location_empty_p (b))
{
delete_breakpoint (b);
continue;
@ -13063,7 +13071,7 @@ static void
bkpt_re_set (struct breakpoint *b)
{
/* FIXME: is this still reachable? */
if (event_location_empty_p (b->location))
if (breakpoint_event_location_empty_p (b))
{
/* Anything without a location can't be re-set. */
delete_breakpoint (b);

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@ -1,3 +1,10 @@
2016-02-09 Keith Seitz <keiths@redhat.com>
PR breakpoints/19546
* gdb.base/infcall-exec.c: New file.
* gdb.base/infcall-exec2.c: New file.
* gdb.base/infcall-exec.exp: New file.
2016-02-09 Keith Seitz <keiths@redhat.com>
* gdb.guile/scm-breakpoint.exp (test_bkpt_address): New procedure.

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@ -0,0 +1,28 @@
/* This test program is part of GDB, the GNU debugger.
Copyright 2016 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <unistd.h>
int
main (int argc, char ** argv)
{
const char *prog = "inf-exec2";
execlp (prog, prog, (char *) 0);
return 0;
}

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@ -0,0 +1,48 @@
# Copyright 2016 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# Test an inferior function call which execs a new program.
# This is a test for breakpoints/19546.
standard_testfile
set testfile2 "infcall-exec2"
set srcfile2 "${testfile2}.c"
set binfile2 [standard_output_file $testfile2]
# Build the two executables for the test.
if {[gdb_compile $srcdir/$subdir/$srcfile $binfile executable debug] != ""} {
untested "could not build $binfile"
return -1
}
if {[gdb_compile $srcdir/$subdir/$srcfile2 $binfile2 executable debug] != ""} {
untested "could not build $binfile2"
return -1
}
clean_restart $binfile
if {![runto_main]} {
untested "could not run to main"
return -1
}
set expected_result "process $decimal is executing new program: $binfile2"
append expected_result "\[\r\n\]+.*"
append expected_result "Breakpoint 1, main .*at .*$srcfile2:$decimal"
append expected_result ".*"
gdb_test "call execlp \(\"$binfile2\", \"$binfile2\", \(char \*\)0\)" \
$expected_result "call execlp"

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@ -0,0 +1,22 @@
/* This test program is part of GDB, the GNU debugger.
Copyright 2016 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
int
main (int argc, char ** argv)
{
return 0;
}