Changeset 82364 in vbox

Timestamp:

Dec 4, 2019 7:31:09 AM (5 years ago)

Author:

vboxsync

Message:

Dev/E1000: Deal with potential overflow of nTxDFetched if we decide (unlikely) to enlarge TX cache beyond 255 entries in the future.

File:

• trunk/src/VBox/Devices/Network/DevE1000.cpp (modified) (2 diffs)

trunk/src/VBox/Devices/Network/DevE1000.cpp

@@ -3933 +3933 @@
     /* We've already loaded pThis->nTxDFetched descriptors past TDH. */
     unsigned nDescsAvailable    = e1kGetTxLen(pThis) - pThis->nTxDFetched;
+    /* The following two lines ensure that pThis->nTxDFetched never overflows. */
+    AssertCompile(E1K_TXD_CACHE_SIZE < (256 * sizeof(pThis->nTxDFetched)));
     unsigned nDescsToFetch      = RT_MIN(nDescsAvailable, E1K_TXD_CACHE_SIZE - pThis->nTxDFetched);
     unsigned nDescsTotal        = TDLEN / sizeof(E1KTXDESC);
@@ -3960 +3962 @@
                  TDBAH, TDBAL));
     }
-    pThis->nTxDFetched += nDescsToFetch;
+    pThis->nTxDFetched += (uint8_t)nDescsToFetch;
     return nDescsToFetch;
 }