Error reporting patches for 2020-04-04

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Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2020-04-04' into staging

Error reporting patches for 2020-04-04

# gpg: Signature made Sat 04 Apr 2020 13:19:40 BST
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-error-2020-04-04:
  qga/commands-posix: fix use after free of local_err
  dump/win_dump: fix use after free of err
  scripts/coccinelle: add error-use-after-free.cocci

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

MAINTAINERS

@@ -2053,6 +2053,11 @@ F: include/qemu/error-report.h
 F: qapi/error.json
 F: util/error.c
 F: util/qemu-error.c
+F: scripts/coccinelle/err-bad-newline.cocci
+F: scripts/coccinelle/error-use-after-free.cocci
+F: scripts/coccinelle/error_propagate_null.cocci
+F: scripts/coccinelle/remove_local_err.cocci
+F: scripts/coccinelle/use-error_fatal.cocci
 
 GDB stub
 M: Alex Bennée <alex.bennee@linaro.org>

dump/win_dump.c

@@ -304,13 +304,11 @@ static void restore_context(WinDumpHeader64 *h,
                             struct saved_context *saved_ctx)
 {
     int i;
-    Error *err = NULL;
 
     for (i = 0; i < h->NumberProcessors; i++) {
         if (cpu_memory_rw_debug(first_cpu, saved_ctx[i].addr,
                 (uint8_t *)&saved_ctx[i].ctx, sizeof(WinContext), 1)) {
-            error_setg(&err, "win-dump: failed to restore CPU #%d context", i);
+            warn_report("win-dump: failed to restore CPU #%d context", i);
-            warn_report_err(err);
         }
     }
 }

qga/commands-posix.c

@@ -1773,6 +1773,7 @@ static void guest_suspend(SuspendMode mode, Error **errp)
     }
 
     error_free(local_err);
+    local_err = NULL;
 
     if (pmutils_supports_mode(mode, &local_err)) {
         mode_supported = true;
@@ -1784,6 +1785,7 @@ static void guest_suspend(SuspendMode mode, Error **errp)
     }
 
     error_free(local_err);
+    local_err = NULL;
 
     if (linux_sys_state_supports_mode(mode, &local_err)) {
         mode_supported = true;
@@ -1791,6 +1793,7 @@ static void guest_suspend(SuspendMode mode, Error **errp)
     }
 
     if (!mode_supported) {
+        error_free(local_err);
         error_setg(errp,
                    "the requested suspend mode is not supported by the guest");
     } else {

scripts/coccinelle/error-use-after-free.cocci

@@ -0,0 +1,52 @@
+// Find and fix trivial use-after-free of Error objects
+//
+// Copyright (c) 2020 Virtuozzo International GmbH.
+//
+// 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 2 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/>.
+//
+// How to use:
+// spatch --sp-file scripts/coccinelle/error-use-after-free.cocci \
+//  --macro-file scripts/cocci-macro-file.h --in-place \
+//  --no-show-diff ( FILES... | --use-gitgrep . )
+
+@ exists@
+identifier fn, fn2;
+expression err;
+@@
+
+ fn(...)
+ {
+     <...
+(
+     error_free(err);
++    err = NULL;
+|
+     error_report_err(err);
++    err = NULL;
+|
+     error_reportf_err(err, ...);
++    err = NULL;
+|
+     warn_report_err(err);
++    err = NULL;
+|
+     warn_reportf_err(err, ...);
++    err = NULL;
+)
+     ... when != err = NULL
+         when != exit(...)
+     fn2(..., err, ...)
+     ...>
+ }