streaming: improve error handling

util-streaming-buffer.c:205:5: warning: Potential leak of memory pointed to by 'sbb2' [unix.Malloc]
    BUG_ON(sbb2->offset < sbb->len);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./suricata-common.h:290:27: note: expanded from macro 'BUG_ON'
        #define BUG_ON(x) assert(!(x))
                          ^~~~~~~~~~~~
/usr/include/assert.h:99:28: note: expanded from macro 'assert'
     ? __ASSERT_VOID_CAST (0)                                           \
                           ^
1 warning generated.

src/util-streaming-buffer.c

@@ -183,26 +183,28 @@ static int WARN_UNUSED SBBInit(StreamingBuffer *sb, uint32_t rel_offset, uint32_
     }
     sbb->offset = sb->stream_offset;
     sbb->len = sb->buf_offset;
+    (void)SBB_RB_INSERT(&sb->sbb_tree, sbb);
+    sb->sbb_size = sbb->len;
+    sb->head = sbb;
 
     StreamingBufferBlock *sbb2 = CALLOC(sb->cfg, 1, sizeof(*sbb2));
     if (sbb2 == NULL) {
-        FREE(sb->cfg, sbb, sizeof(*sbb));
         return -1;
     }
     sbb2->offset = sb->stream_offset + rel_offset;
     sbb2->len = data_len;
-
-    sb->head = sbb;
-    sb->sbb_size = sbb->len + sbb2->len;
-    SBB_RB_INSERT(&sb->sbb_tree, sbb);
-    SBB_RB_INSERT(&sb->sbb_tree, sbb2);
-
     SCLogDebug("sbb1 %"PRIu64", len %u, sbb2 %"PRIu64", len %u",
             sbb->offset, sbb->len, sbb2->offset, sbb2->len);
+
+    sb->sbb_size += sbb2->len;
+    if (SBB_RB_INSERT(&sb->sbb_tree, sbb2) != NULL) {
+        FREE(sb->cfg, sbb2, sizeof(*sbb2));
+        return -1;
+    }
+
 #ifdef DEBUG
     SBBPrintList(sb);
 #endif
-    BUG_ON(sbb2->offset < sbb->len);
     return 0;
 }
 
@@ -222,7 +224,7 @@ static int WARN_UNUSED SBBInitLeadingGap(StreamingBuffer *sb, uint64_t offset, u
 
     sb->head = sbb;
     sb->sbb_size = sbb->len;
-    SBB_RB_INSERT(&sb->sbb_tree, sbb);
+    (void)SBB_RB_INSERT(&sb->sbb_tree, sbb);
 
     SCLogDebug("sbb %"PRIu64", len %u",
             sbb->offset, sbb->len);