[xen stable-4.17] tools/ocaml/libs: Allocate the correct amount of memory for Abstract_tag

[patchbot@xxxxxxx]

commit 5797b798a542a7e5be34698463152cb92f18776f
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue Jan 31 10:59:42 2023 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Feb 9 15:55:25 2023 +0000

    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@xxxxxxxxxx>
    Acked-by: Christian Lindig <christian.lindig@xxxxxxxxxx>
    (cherry picked from commit 36eb2de31b6ecb8787698fb1a701bd708c8971b2)
---
 tools/ocaml/libs/mmap/Makefile        | 2 ++
 tools/ocaml/libs/mmap/xenmmap_stubs.c | 6 +++++-
 tools/ocaml/libs/xc/xenctrl_stubs.c   | 5 ++++-
 3 files changed, 11 insertions(+), 2 deletions(-)

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 6eb0ea69da..e25367531b 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -956,7 +956,10 @@ 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);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.17