[PULL 14/17] migration/ram: Use offset_in_ramblock() in range checks

[Dr. David Alan Gilbert (git)]

From: David Hildenbrand <david@redhat.com>

We never read or write beyond the used_length of memory blocks when
migrating. Make this clearer by using offset_in_ramblock() consistently.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210429112708.12291-11-david@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/ram.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 6d09ca78bc..60ea913c54 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1342,8 +1342,8 @@ static bool find_dirty_block(RAMState *rs, 
PageSearchStatus *pss, bool *again)
         *again = false;
         return false;
     }
-    if ((((ram_addr_t)pss->page) << TARGET_PAGE_BITS)
-        >= pss->block->used_length) {
+    if (!offset_in_ramblock(pss->block,
+                            ((ram_addr_t)pss->page) << TARGET_PAGE_BITS)) {
         /* Didn't find anything in this RAM Block */
         pss->page = 0;
         pss->block = QLIST_NEXT_RCU(pss->block, next);
@@ -1863,7 +1863,7 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t 
start, ram_addr_t len)
         rs->last_req_rb = ramblock;
     }
     trace_ram_save_queue_pages(ramblock->idstr, start, len);
-    if (start + len > ramblock->used_length) {
+    if (!offset_in_ramblock(ramblock, start + len - 1)) {
         error_report("%s request overrun start=" RAM_ADDR_FMT " len="
                      RAM_ADDR_FMT " blocklen=" RAM_ADDR_FMT,
                      __func__, start, len, ramblock->used_length);
@@ -3696,8 +3696,8 @@ void colo_flush_ram_cache(void)
         while (block) {
             offset = migration_bitmap_find_dirty(ram_state, block, offset);
 
-            if (((ram_addr_t)offset) << TARGET_PAGE_BITS
-                >= block->used_length) {
+            if (!offset_in_ramblock(block,
+                                    ((ram_addr_t)offset) << TARGET_PAGE_BITS)) 
{
                 offset = 0;
                 block = QLIST_NEXT_RCU(block, next);
             } else {
-- 
2.31.1