From 6be2f51c147df1ab1dd7c68c6b554512dfc05e6f Mon Sep 17 00:00:00 2001
From: Hanna Czenczek <hreitz@redhat.com>
Date: Tue, 15 Oct 2024 19:04:37 +0200
Subject: [PATCH 1/9] migration: Ensure vmstate_save() sets errp
RH-Author: Hanna Czenczek <hreitz@redhat.com>
RH-MergeRequest: 288: migration: Ensure vmstate_save() sets errp
RH-Jira: RHEL-63051
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: German Maglione <None>
RH-Commit: [1/1] 4d5a65c294ae83a29db885e42fb3f2ca913c36f0 (hreitz/qemu-kvm-c-9-s)
migration/savevm.c contains some calls to vmstate_save() that are
followed by migrate_set_error() if the integer return value indicates an
error. migrate_set_error() requires that the `Error *` object passed to
it is set. Therefore, vmstate_save() is assumed to always set *errp on
error.
Right now, that assumption is not met: vmstate_save_state_v() (called
internally by vmstate_save()) will not set *errp if
vmstate_subsection_save() or vmsd->post_save() fail. Fix that by adding
an *errp parameter to vmstate_subsection_save(), and by generating a
generic error in case post_save() fails (as is already done for
pre_save()).
Without this patch, qemu will crash after vmstate_subsection_save() or
post_save() have failed inside of a vmstate_save() call (unless
migrate_set_error() then happen to discard the new error because
s->error is already set). This happens e.g. when receiving the state
from a virtio-fs back-end (virtiofsd) fails.
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Link: https://lore.kernel.org/r/20241015170437.310358-1-hreitz@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
(cherry picked from commit 37dfcba1a04989830c706f9cbc00450e5d3a7447)
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
---
migration/vmstate.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/migration/vmstate.c b/migration/vmstate.c
index ff5d589a6d..fa002b24e8 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -22,7 +22,8 @@
#include "trace.h"
static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
- void *opaque, JSONWriter *vmdesc);
+ void *opaque, JSONWriter *vmdesc,
+ Error **errp);
static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque);
@@ -441,12 +442,13 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
json_writer_end_array(vmdesc);
}
- ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc);
+ ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc, errp);
if (vmsd->post_save) {
int ps_ret = vmsd->post_save(opaque);
- if (!ret) {
+ if (!ret && ps_ret) {
ret = ps_ret;
+ error_setg(errp, "post-save failed: %s", vmsd->name);
}
}
return ret;
@@ -518,7 +520,8 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
}
static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
- void *opaque, JSONWriter *vmdesc)
+ void *opaque, JSONWriter *vmdesc,
+ Error **errp)
{
const VMStateDescription * const *sub = vmsd->subsections;
bool vmdesc_has_subsections = false;
@@ -546,7 +549,7 @@ static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
qemu_put_be32(f, vmsdsub->version_id);
- ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
+ ret = vmstate_save_state_with_err(f, vmsdsub, opaque, vmdesc, errp);
if (ret) {
return ret;
}
--
2.39.3