defrag: fix check for complete packet

The list of fragments may still contain overlaps, so adding up the
fragment lengths is flawed. Instead track the largest size of
contiguous data that can be re-assembled.

Bug: #6675

diff --git a/src/defrag.c b/src/defrag.c
index 594c9d0dd942d8e128909f63d414d11190c5be8c..fede1b927a0cebd3552b141fceb0013ad528a8d9 100644 (file)
--- a/src/defrag.c
+++ b/src/defrag.c
@@ -256,7 +256,8 @@ Defrag4Reassemble(ThreadVars *tv, DefragTracker *tracker, Packet *p)
             goto done;
         }
         else {
-            len += frag->data_len;
+            /* Update the packet length to the largest known data offset. */
+            len = MAX(len, frag->offset + frag->data_len);
         }
     }
 
@@ -414,7 +415,7 @@ Defrag6Reassemble(ThreadVars *tv, DefragTracker *tracker, Packet *p)
                 goto done;
             }
             else {
-                len += frag->data_len;
+                len = MAX(len, frag->offset + frag->data_len);
             }
         }
     }
@@ -3057,6 +3058,116 @@ static int DefragBsdSubsequentOverlapsStartOfOriginalIpv6Test(void)
     PASS;
 }
 
+/**
+ * Reassembly should fail.
+ *
+ * |0       |8       |16      |24      |32      |40      |48      |
+ * |========|========|========|========|========|========|========|
+ * |        |        |AABBCCDD|AABBDDCC|        |        |        |
+ * |        |        |        |        |        |AACCBBDD|        |
+ * |        |AACCDDBB|AADDBBCC|        |        |        |        |
+ * |ZZZZZZZZ|        |        |        |        |        |        |
+ * |        |        |        |        |        |        |DDCCBBAA|
+ */
+static int DefragBsdMissingFragmentIpv4Test(void)
+{
+    DefragInit();
+    default_policy = DEFRAG_POLICY_BSD;
+    Packet *packets[5];
+
+    FAIL_IF_NOT(BuildIpv4TestPacketWithContent(
+            &packets[0], IPPROTO_ICMP, 189, 16 >> 3, 1, (uint8_t *)"AABBCCDDAABBDDCC", 16));
+
+    FAIL_IF_NOT(BuildIpv4TestPacketWithContent(
+            &packets[1], IPPROTO_ICMP, 189, 40 >> 3, 1, (uint8_t *)"AACCBBDD", 8));
+
+    FAIL_IF_NOT(BuildIpv4TestPacketWithContent(
+            &packets[2], IPPROTO_ICMP, 189, 8 >> 3, 1, (uint8_t *)"AACCDDBBAADDBBCC", 16));
+
+    /* ICMP header. */
+    FAIL_IF_NOT(BuildIpv4TestPacketWithContent(
+            &packets[3], IPPROTO_ICMP, 189, 0, 1, (uint8_t *)"ZZZZZZZZ", 8));
+
+    FAIL_IF_NOT(BuildIpv4TestPacketWithContent(
+            &packets[4], IPPROTO_ICMP, 189, 48 >> 3, 0, (uint8_t *)"DDCCBBAA", 8));
+
+    Packet *r = Defrag(NULL, NULL, packets[0]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[1]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[2]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[3]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[4]);
+    FAIL_IF_NOT_NULL(r);
+
+#if 0
+    PrintRawDataFp(stdout, GET_PKT_DATA(r) + 20, GET_PKT_LEN(r) - 20);
+#endif
+
+    for (int i = 0; i < 5; i++) {
+        SCFree(packets[i]);
+    }
+
+    DefragDestroy();
+
+    PASS;
+}
+
+static int DefragBsdMissingFragmentIpv6Test(void)
+{
+    DefragInit();
+    default_policy = DEFRAG_POLICY_BSD;
+    Packet *packets[5];
+
+    packets[0] = BuildIpv6TestPacketWithContent(
+            IPPROTO_ICMP, 189, 16 >> 3, 1, (uint8_t *)"AABBCCDDAABBDDCC", 16);
+
+    packets[1] =
+            BuildIpv6TestPacketWithContent(IPPROTO_ICMP, 189, 40 >> 3, 1, (uint8_t *)"AACCBBDD", 8);
+
+    packets[2] = BuildIpv6TestPacketWithContent(
+            IPPROTO_ICMP, 189, 8 >> 3, 1, (uint8_t *)"AACCDDBBAADDBBCC", 16);
+
+    /* ICMP header. */
+    packets[3] = BuildIpv6TestPacketWithContent(IPPROTO_ICMP, 189, 0, 1, (uint8_t *)"ZZZZZZZZ", 8);
+
+    packets[4] =
+            BuildIpv6TestPacketWithContent(IPPROTO_ICMP, 189, 48 >> 3, 0, (uint8_t *)"DDCCBBAA", 8);
+
+    Packet *r = Defrag(NULL, NULL, packets[0]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[1]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[2]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[3]);
+    FAIL_IF_NOT_NULL(r);
+
+    r = Defrag(NULL, NULL, packets[4]);
+    FAIL_IF_NOT_NULL(r);
+
+#if 0
+    PrintRawDataFp(stdout, GET_PKT_DATA(r) + 40, GET_PKT_LEN(r) - 40);
+#endif
+
+    for (int i = 0; i < 5; i++) {
+        SCFree(packets[i]);
+    }
+
+    DefragDestroy();
+
+    PASS;
+}
+
 #endif /* UNITTESTS */
 
 void DefragRegisterTests(void)
@@ -3107,5 +3218,7 @@ void DefragRegisterTests(void)
             DefragBsdSubsequentOverlapsStartOfOriginalIpv4Test_2);
     UtRegisterTest("DefragBsdSubsequentOverlapsStartOfOriginalIpv6Test_2",
             DefragBsdSubsequentOverlapsStartOfOriginalIpv6Test_2);
+    UtRegisterTest("DefragBsdMissingFragmentIpv4Test", DefragBsdMissingFragmentIpv4Test);
+    UtRegisterTest("DefragBsdMissingFragmentIpv6Test", DefragBsdMissingFragmentIpv6Test);
 #endif /* UNITTESTS */
 }