zcore.patch

diff --git a/src/lib/process_builder/src/lib.rs b/src/lib/process_builder/src/lib.rs
index 0d49b5bf37a..7929530fe6e 100644
--- a/src/lib/process_builder/src/lib.rs
+++ b/src/lib/process_builder/src/lib.rs
@@ -834,7 +834,7 @@ impl ReservationVmar {
         // (base+len) represents the full address space, assuming this is used with a root VMAR and
         // length extends to the end of the address space, including a region the kernel reserves
         // at the start of the space.
-        let reserve_size = util::page_end((info.base + info.len) / 2) - info.base;
+        let reserve_size = util::page_end(info.len / 2);
         let (reserve_vmar, reserve_base) =
             vmar.allocate(0, reserve_size, zx::VmarFlags::SPECIFIC).map_err(|s| {
                 ProcessBuilderError::GenericStatus("Failed to allocate reservation VMAR", s)
diff --git a/zircon/kernel/lib/userabi/userboot/start.cc b/zircon/kernel/lib/userabi/userboot/start.cc
index 70188140fe1..777eccb1403 100644
--- a/zircon/kernel/lib/userabi/userboot/start.cc
+++ b/zircon/kernel/lib/userabi/userboot/start.cc
@@ -81,9 +81,9 @@ zx_handle_t reserve_low_address_space(zx_handle_t log, zx_handle_t root_vmar) {
         "zx_object_get_info failed on child root VMAR handle");
   zx_handle_t vmar;
   uintptr_t addr;
-  size_t reserve_size = (((info.base + info.len) / 2) + PAGE_SIZE - 1) & -PAGE_SIZE;
+  size_t reserve_size = (info.len / 2 + PAGE_SIZE - 1) & -PAGE_SIZE;
   zx_status_t status =
-      zx_vmar_allocate(root_vmar, ZX_VM_SPECIFIC, 0, reserve_size - info.base, &vmar, &addr);
+      zx_vmar_allocate(root_vmar, ZX_VM_SPECIFIC, 0, reserve_size, &vmar, &addr);
   check(log, status, "zx_vmar_allocate failed for low address space reservation");
   if (addr != info.base)
     fail(log, "zx_vmar_allocate gave wrong address?!?");
diff --git a/zircon/system/ulib/launchpad/launchpad.c b/zircon/system/ulib/launchpad/launchpad.c
index 1a538fadc53..c465e6ae5c4 100644
--- a/zircon/system/ulib/launchpad/launchpad.c
+++ b/zircon/system/ulib/launchpad/launchpad.c
@@ -468,8 +468,8 @@ static zx_status_t reserve_low_address_space(launchpad_t* lp) {
   }
 
   uintptr_t addr;
-  size_t reserve_size = (((info.base + info.len) / 2) + PAGE_SIZE - 1) & -PAGE_SIZE;
-  status = zx_vmar_allocate(lp_vmar(lp), ZX_VM_SPECIFIC, 0, reserve_size - info.base,
+  size_t reserve_size = (info.len / 2 + PAGE_SIZE - 1) & -PAGE_SIZE;
+  status = zx_vmar_allocate(lp_vmar(lp), ZX_VM_SPECIFIC, 0, reserve_size,
                             &lp->reserve_vmar, &addr);
   if (status != ZX_OK) {
     return lp_error(lp, status, "zx_vmar_allocate failed for low address space reservation");