3 files changed, 36 insertions, 40 deletions

diff --git a/erts/emulator/beam/erl_alloc_util.c b/erts/emulator/beam/erl_alloc_util.c
index 8d4464969a..25ac3bc5af 100644
--- a/erts/emulator/beam/erl_alloc_util.c
+++ b/erts/emulator/beam/erl_alloc_util.c
@@ -6567,6 +6567,14 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
                  __FILE__, __LINE__);
     }
 
+    /* The various fields packed into the header word must not overlap */
+    ERTS_CT_ASSERT(!(MBC_ABLK_OFFSET_MASK & MBC_ABLK_SZ_MASK));
+    ERTS_CT_ASSERT(!(MBC_ABLK_OFFSET_MASK & BLK_FLG_MASK));
+    ERTS_CT_ASSERT(!(MBC_ABLK_SZ_MASK & BLK_FLG_MASK));
+    ERTS_CT_ASSERT(!(MBC_FBLK_SZ_MASK & BLK_FLG_MASK));
+    ERTS_CT_ASSERT(!(SBC_BLK_SZ_MASK & BLK_FLG_MASK));
+    ERTS_CT_ASSERT(!(CRR_SZ_MASK & CRR_FLG_MASK));
+
     if (!initialized)
 	goto error;
 
diff --git a/erts/emulator/beam/erl_alloc_util.h b/erts/emulator/beam/erl_alloc_util.h
index ea1afe8f58..b34916271e 100644
--- a/erts/emulator/beam/erl_alloc_util.h
+++ b/erts/emulator/beam/erl_alloc_util.h
@@ -334,8 +334,9 @@ void erts_alcu_sched_spec_data_init(struct ErtsSchedulerData_ *esdp);
 #endif
 
 #if MBC_ABLK_OFFSET_BITS
-#  define MBC_ABLK_OFFSET_SHIFT  (sizeof(UWord)*8 - MBC_ABLK_OFFSET_BITS)
-#  define MBC_ABLK_OFFSET_MASK   ((~((UWord)0) << MBC_ABLK_OFFSET_SHIFT) & ~BLK_FLG_MASK)
+/* The shift is reduced by 1 since the highest bit is used for a flag. */
+#  define MBC_ABLK_OFFSET_SHIFT  (sizeof(UWord)*8 - 1 - MBC_ABLK_OFFSET_BITS)
+#  define MBC_ABLK_OFFSET_MASK   (((1ul << MBC_ABLK_OFFSET_BITS) - 1ul) << MBC_ABLK_OFFSET_SHIFT)
 #  define MBC_ABLK_SZ_MASK	(~MBC_ABLK_OFFSET_MASK & ~BLK_FLG_MASK)
 #else
 #  define MBC_ABLK_SZ_MASK	(~BLK_FLG_MASK)
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index 31c941337f..45fef0c0e5 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -5298,44 +5298,31 @@ erts_get_port_names(Eterm id, ErlDrvPort drv_port)
 	pnp->driver_name = NULL;
     }
     else {
-	int do_realloc = 1;
-	int len = -1;
-	size_t pnp_len = sizeof(ErtsPortNames);
-#ifndef DEBUG
-	pnp_len += 100; /* In most cases 100 characters will be enough... */
-	ASSERT(prt->common.id == id);
-#endif
-	pnp = erts_alloc(ERTS_ALC_T_PORT_NAMES, pnp_len);
-	do {
-	    int nlen;
-	    char *name, *driver_name;
-	    if (len > 0) {
-		erts_free(ERTS_ALC_T_PORT_NAMES, pnp);
-		pnp_len = sizeof(ErtsPortNames) + len;
-		pnp = erts_alloc(ERTS_ALC_T_PORT_NAMES, pnp_len);
-	    }
-	    name = prt->name;
-	    len = nlen = name ? sys_strlen(name) + 1 : 0;
-	    driver_name = (prt->drv_ptr ? prt->drv_ptr->name : NULL);
-	    len += driver_name ? sys_strlen(driver_name) + 1 : 0;
-	    if (len <= pnp_len - sizeof(ErtsPortNames)) {
-		if (!name)
-		    pnp->name = NULL;
-		else {
-		    pnp->name = ((char *) pnp) + sizeof(ErtsPortNames);
-		    sys_strcpy(pnp->name, name);
-		}
-		if (!driver_name)
-		    pnp->driver_name = NULL;
-		else {
-		    pnp->driver_name = (((char *) pnp)
-					+ sizeof(ErtsPortNames)
-					+ nlen);
-		    sys_strcpy(pnp->driver_name, driver_name);
-		}
-		do_realloc = 0;
-	    }
-	} while (do_realloc);
+	int len;
+        int nlen;
+        char *driver_name;
+
+        len = nlen = prt->name ? sys_strlen(prt->name) + 1 : 0;
+        driver_name = (prt->drv_ptr ? prt->drv_ptr->name : NULL);
+        len += driver_name ? sys_strlen(driver_name) + 1 : 0;
+
+        pnp = erts_alloc(ERTS_ALC_T_PORT_NAMES,
+                         sizeof(ErtsPortNames) + len);
+
+        if (!prt->name)
+            pnp->name = NULL;
+        else {
+            pnp->name = ((char *) pnp) + sizeof(ErtsPortNames);
+            sys_strcpy(pnp->name, prt->name);
+        }
+        if (!driver_name)
+            pnp->driver_name = NULL;
+        else {
+            pnp->driver_name = (((char *) pnp)
+                                + sizeof(ErtsPortNames)
+                                + nlen);
+            sys_strcpy(pnp->driver_name, driver_name);
+        }
     }
     return pnp;
 }