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qdev: Fix crash in array property getter

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Passing an uninitialised list to visit_start_list() happens to work for
the QObject output visitor because it treats the pointer as an opaque
value and never dereferences it, but the string output visitor expects a
valid list to check if it has more than one element.

The existing code crashes with the string output visitor if the
uninitialised value is non-NULL. Passing an explicit NULL would fix the
crash, but still result in wrong output.

Rework get_prop_array() so that it conforms to the expectations that the
string output visitor has. This includes building a real list first and
using visit_next_list() to iterate it.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1993
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Tested-by: Dan Hoffman <dhoff749@gmail.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20231121173416.346610-2-kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-11-21 18:34:15 +01:00 committed by Stefan Hajnoczi
parent e867b01cd6
commit 50571883f6
1 changed files with 26 additions and 7 deletions
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33
hw/core/qdev-properties.c
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@ -689,23 +689,36 @@ static void get_prop_array(Object *obj, Visitor *v, const char *name,
Property *prop = opaque;
uint32_t *alenptr = object_field_prop_ptr(obj, prop);
void **arrayptr = (void *)obj + prop->arrayoffset;
char *elem = *arrayptr;
GenericList *list;
const size_t list_elem_size = sizeof(*list) + prop->arrayfieldsize;
char *elemptr = *arrayptr;
ArrayElementList *list = NULL, *elem;
ArrayElementList **tail = &list;
const size_t size = sizeof(*list);
int i;
bool ok;
if (!visit_start_list(v, name, &list, list_elem_size, errp)) {
/* At least the string output visitor needs a real list */
for (i = 0; i < *alenptr; i++) {
elem = g_new0(ArrayElementList, 1);
elem->value = elemptr;
elemptr += prop->arrayfieldsize;
*tail = elem;
tail = &elem->next;
}
if (!visit_start_list(v, name, (GenericList **) &list, size, errp)) {
return;
}
for (i = 0; i < *alenptr; i++) {
Property elem_prop = array_elem_prop(obj, prop, name, elem);
elem = list;
while (elem) {
Property elem_prop = array_elem_prop(obj, prop, name, elem->value);
prop->arrayinfo->get(obj, v, NULL, &elem_prop, errp);
if (*errp) {
goto out_obj;
}
elem += prop->arrayfieldsize;
elem = (ArrayElementList *) visit_next_list(v, (GenericList*) elem,
size);
}
/* visit_check_list() can only fail for input visitors */
@ -714,6 +727,12 @@ static void get_prop_array(Object *obj, Visitor *v, const char *name,
out_obj:
visit_end_list(v, (void**) &list);
while (list) {
elem = list;
list = elem->next;
g_free(elem);
}
}
static void default_prop_array(ObjectProperty *op, const Property *prop)