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Check that typed item fits on UTCB, issue #248 

Check that there is enough room for a typed item on the
UTCB. Otherwise deny to add the item and return false.
Enable explicitly a return unused warning to get the right
attention.
This commit is contained in:
Alexander Boettcher 2012-06-20 16:26:24 +02:00 committed by Norman Feske
parent 0c2adf7ddd
commit 9ebbf9c9f2
1 changed files with 9 additions and 1 deletions
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10
base-nova/include/nova/syscall-generic.h
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@ -403,7 +403,8 @@ namespace Nova {
*
* \param exception true to append the item to an exception reply
*/
void append_item(Crd crd, mword_t sel_hotspot,
__attribute__((warn_unused_result))
bool append_item(Crd crd, mword_t sel_hotspot,
bool kern_pd = false,
bool update_guest_pt = false)
{
@ -411,6 +412,12 @@ namespace Nova {
items += 1 << 16;
Item *item = reinterpret_cast<Item *>(this) + (PAGE_SIZE_BYTE / sizeof(struct Item)) - (items >> 16);
/* check that there is enough space left on UTCB */
if (msg + msg_words() >= reinterpret_cast<mword_t *>(item)) {
items -= 1 << 16;
return false;
}
/* map from hypervisor or current pd */
unsigned h = kern_pd ? (1 << 11) : 0;
@ -420,6 +427,7 @@ namespace Nova {
item->hotspot = crd.hotspot(sel_hotspot) | g | h | 1;
item->crd = crd.value();
return true;
}
mword_t mtd_value() const { return static_cast<Mtd>(mtd).value(); }