[PATCH] tools/libxengnttab: correct size of allocated memory

From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wl@xen.org>
Subject: [PATCH] tools/libxengnttab: correct size of allocated memory
Date: Wed, 20 May 2020 10:35:01 +0200	[thread overview]
Message-ID: <20200520083501.31704-1-jgross@suse.com> (raw)

The size of the memory allocated for the IOCTL_GNTDEV_MAP_GRANT_REF
ioctl() parameters is calculated wrong, which results in too much
memory allocated.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 tools/libs/gnttab/freebsd.c | 2 +-
 tools/libs/gnttab/linux.c   | 8 +++-----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/tools/libs/gnttab/freebsd.c b/tools/libs/gnttab/freebsd.c
index 886b588303..0588501d0f 100644
--- a/tools/libs/gnttab/freebsd.c
+++ b/tools/libs/gnttab/freebsd.c
@@ -74,7 +74,7 @@ void *osdep_gnttab_grant_map(xengnttab_handle *xgt,
     void *addr = NULL;
     int domids_stride;
     unsigned int refs_size = ROUNDUP(count *
-                                     sizeof(struct ioctl_gntdev_map_grant_ref),
+                                     sizeof(struct ioctl_gntdev_grant_ref),
                                      PAGE_SHIFT);
 
     domids_stride = (flags & XENGNTTAB_GRANT_MAP_SINGLE_DOMAIN) ? 0 : 1;
diff --git a/tools/libs/gnttab/linux.c b/tools/libs/gnttab/linux.c
index a01bb6c698..74331a4c7b 100644
--- a/tools/libs/gnttab/linux.c
+++ b/tools/libs/gnttab/linux.c
@@ -91,9 +91,7 @@ void *osdep_gnttab_grant_map(xengnttab_handle *xgt,
 {
     int fd = xgt->fd;
     struct ioctl_gntdev_map_grant_ref *map;
-    unsigned int map_size = ROUNDUP((sizeof(*map) + (count - 1) *
-                                    sizeof(struct ioctl_gntdev_map_grant_ref)),
-                                    PAGE_SHIFT);
+    unsigned int map_size = sizeof(*map) + (count - 1) * sizeof(map->refs[0]);
     void *addr = NULL;
     int domids_stride = 1;
     int i;
@@ -102,10 +100,10 @@ void *osdep_gnttab_grant_map(xengnttab_handle *xgt,
         domids_stride = 0;
 
     if ( map_size <= PAGE_SIZE )
-        map = alloca(sizeof(*map) +
-                     (count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
+        map = alloca(map_size);
     else
     {
+        map_size = ROUNDUP(map_size, PAGE_SHIFT);
         map = mmap(NULL, map_size, PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_ANON | MAP_POPULATE, -1, 0);
         if ( map == MAP_FAILED )
-- 
2.26.1


