From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Tue, 31 Jan 2023 10:59:42 +0000 (+0000)
Subject: tools/ocaml/libs: Allocate the correct amount of memory for Abstract_tag
X-Git-Tag: 4.18.0-rc1~1134
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=36eb2de31b6ecb8787698fb1a701bd708c8971b2;p=xen.git

tools/ocaml/libs: Allocate the correct amount of memory for Abstract_tag

caml_alloc() takes units of Wsize (word size), not bytes.  As a consequence,
we're allocating 4 or 8 times too much memory.

Ocaml has a helper, Wsize_bsize(), but it truncates cases which aren't an
exact multiple.  Use a BUILD_BUG_ON() to cover the potential for truncation,
as there's no rounding-up form of the helper.

Fixes: 8b7ce06a2d34 ("ocaml: Add XC bindings.")
Fixes: d3e649277a13 ("ocaml: add mmap bindings implementation.")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
---

diff --git a/tools/ocaml/libs/mmap/Makefile b/tools/ocaml/libs/mmap/Makefile
index a621537135..855b8b2c98 100644
--- a/tools/ocaml/libs/mmap/Makefile
+++ b/tools/ocaml/libs/mmap/Makefile
@@ -2,6 +2,8 @@ OCAML_TOPLEVEL=$(CURDIR)/../..
 XEN_ROOT=$(OCAML_TOPLEVEL)/../..
 include $(OCAML_TOPLEVEL)/common.make
 
+CFLAGS += $(CFLAGS_xeninclude)
+
 OBJS = xenmmap
 INTF = $(foreach obj, $(OBJS),$(obj).cmi)
 LIBS = xenmmap.cma xenmmap.cmxa
diff --git a/tools/ocaml/libs/mmap/xenmmap_stubs.c b/tools/ocaml/libs/mmap/xenmmap_stubs.c
index e03951d781..d623ad390e 100644
--- a/tools/ocaml/libs/mmap/xenmmap_stubs.c
+++ b/tools/ocaml/libs/mmap/xenmmap_stubs.c
@@ -21,6 +21,8 @@
 #include <errno.h>
 #include "mmap_stubs.h"
 
+#include <xen-tools/libs.h>
+
 #include <caml/mlvalues.h>
 #include <caml/memory.h>
 #include <caml/alloc.h>
@@ -59,7 +61,9 @@ CAMLprim value stub_mmap_init(value fd, value pflag, value mflag,
 	default: caml_invalid_argument("maptype");
 	}
 
-	result = caml_alloc(sizeof(struct mmap_interface), Abstract_tag);
+	BUILD_BUG_ON((sizeof(struct mmap_interface) % sizeof(value)) != 0);
+	result = caml_alloc(Wsize_bsize(sizeof(struct mmap_interface)),
+			    Abstract_tag);
 
 	if (mmap_interface_init(Intf_val(result), Int_val(fd),
 	                        c_pflag, c_mflag,
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 7288184459..fd1f306f02 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -1031,7 +1031,10 @@ CAMLprim value stub_map_foreign_range(value xch, value dom,
 	uint32_t c_dom;
 	unsigned long c_mfn;
 
-	result = caml_alloc(sizeof(struct mmap_interface), Abstract_tag);
+	BUILD_BUG_ON((sizeof(struct mmap_interface) % sizeof(value)) != 0);
+	result = caml_alloc(Wsize_bsize(sizeof(struct mmap_interface)),
+			    Abstract_tag);
+
 	intf = (struct mmap_interface *) result;
 
 	intf->len = Int_val(size);