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183be22290
I stumbled on a bug caused by the fact that a code path read
target_waitstatus::value::sig (expecting it to contain a gdb_signal
value) while target_waitstatus::kind was TARGET_WAITKIND_FORKED. This
meant that the active union field was in fact
target_waitstatus::value::related_pid, and contained a ptid. The read
signal value was therefore garbage, and that caused GDB to crash soon
after. Or, since that GDB was built with ubsan, this nice error
message:
/home/simark/src/binutils-gdb/gdb/linux-nat.c:1271:12: runtime error: load of value 2686365, which is not a valid value for type 'gdb_signal'
Despite being a large-ish change, I think it would be nice to make
target_waitstatus safe against that kind of bug. As already done
elsewhere (e.g. dynamic_prop), validate that the type of value read from
the union matches what is supposed to be the active field.
- Make the kind and value of target_waitstatus private.
- Make the kind initialized to TARGET_WAITKIND_IGNORE on
target_waitstatus construction. This is what most users appear to do
explicitly.
- Add setters, one for each kind. Each setter takes as a parameter the
data associated to that kind, if any. This makes it impossible to
forget to attach the associated data.
- Add getters, one for each associated data type. Each getter
validates that the data type fetched by the user matches the wait
status kind.
- Change "integer" to "exit_status", "related_pid" to "child_ptid",
just because that's more precise terminology.
- Fix all users.
That last point is semi-mechanical. There are a lot of obvious changes,
but some less obvious ones. For example, it's not possible to set the
kind at some point and the associated data later, as some users did.
But in any case, the intent of the code should not change in this patch.
This was tested on x86-64 Linux (unix, native-gdbserver and
native-extended-gdbserver boards). It was built-tested on x86-64
FreeBSD, NetBSD, MinGW and macOS. The rest of the changes to native
files was done as a best effort. If I forgot any place to update in
these files, it should be easy to fix (unless the change happens to
reveal an actual bug).
Change-Id: I0ae967df1ff6e28de78abbe3ac9b4b2ff4ad03b7
93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
/* Target waitstatus implementations.
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Copyright (C) 1990-2021 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "gdbsupport/common-defs.h"
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#include "waitstatus.h"
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/* Return a pretty printed form of target_waitstatus. */
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std::string
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target_waitstatus_to_string (const struct target_waitstatus *ws)
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{
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const char *kind_str = "status->kind = ";
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switch (ws->kind ())
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{
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case TARGET_WAITKIND_EXITED:
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return string_printf ("%sexited, status = %d",
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kind_str, ws->exit_status ());
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case TARGET_WAITKIND_STOPPED:
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return string_printf ("%sstopped, signal = %s",
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kind_str,
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gdb_signal_to_symbol_string (ws->sig ()));
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case TARGET_WAITKIND_SIGNALLED:
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return string_printf ("%ssignalled, signal = %s",
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kind_str,
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gdb_signal_to_symbol_string (ws->sig ()));
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case TARGET_WAITKIND_LOADED:
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return string_printf ("%sloaded", kind_str);
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case TARGET_WAITKIND_FORKED:
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return string_printf ("%sforked, child_ptid = %s", kind_str,
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ws->child_ptid ().to_string ().c_str ());
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case TARGET_WAITKIND_VFORKED:
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return string_printf ("%svforked, child_ptid = %s", kind_str,
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ws->child_ptid ().to_string ().c_str ());
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case TARGET_WAITKIND_EXECD:
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return string_printf ("%sexecd, execd_pathname = %s", kind_str,
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ws->execd_pathname ());
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case TARGET_WAITKIND_VFORK_DONE:
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return string_printf ("%svfork-done", kind_str);
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case TARGET_WAITKIND_SYSCALL_ENTRY:
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return string_printf ("%sentered syscall", kind_str);
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case TARGET_WAITKIND_SYSCALL_RETURN:
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return string_printf ("%sexited syscall", kind_str);
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case TARGET_WAITKIND_SPURIOUS:
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return string_printf ("%sspurious", kind_str);
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case TARGET_WAITKIND_IGNORE:
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return string_printf ("%signore", kind_str);
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case TARGET_WAITKIND_NO_HISTORY:
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return string_printf ("%sno-history", kind_str);
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case TARGET_WAITKIND_NO_RESUMED:
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return string_printf ("%sno-resumed", kind_str);
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case TARGET_WAITKIND_THREAD_CREATED:
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return string_printf ("%sthread created", kind_str);
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case TARGET_WAITKIND_THREAD_EXITED:
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return string_printf ("%sthread exited, status = %d",
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kind_str, ws->exit_status ());
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default:
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return string_printf ("%sunknown???", kind_str);
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}
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}
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