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authorElena Reshetova <elena.reshetova@intel.com>2017-03-06 16:21:16 +0200
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2017-03-13 12:45:18 -0400
commitc5f7c5a9a0f84c511a8a336491f9b8a3060b6517 (patch)
tree8c96894513de6ecef4ca4cd333e1a5840ca94fb7 /drivers/xen
parent4495c08e84729385774601b5146d51d9e5849f81 (diff)
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drivers, xen: convert grant_map.users from atomic_t to refcount_t
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: David Windsor <dwindsor@gmail.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/gntdev.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index c77a0751a311..f3bf8f4e2d6c 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -36,6 +36,7 @@
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/highmem.h>
+#include <linux/refcount.h>
#include <xen/xen.h>
#include <xen/grant_table.h>
@@ -86,7 +87,7 @@ struct grant_map {
int index;
int count;
int flags;
- atomic_t users;
+ refcount_t users;
struct unmap_notify notify;
struct ioctl_gntdev_grant_ref *grants;
struct gnttab_map_grant_ref *map_ops;
@@ -166,7 +167,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
add->index = 0;
add->count = count;
- atomic_set(&add->users, 1);
+ refcount_set(&add->users, 1);
return add;
@@ -212,7 +213,7 @@ static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
if (!map)
return;
- if (!atomic_dec_and_test(&map->users))
+ if (!refcount_dec_and_test(&map->users))
return;
atomic_sub(map->count, &pages_mapped);
@@ -400,7 +401,7 @@ static void gntdev_vma_open(struct vm_area_struct *vma)
struct grant_map *map = vma->vm_private_data;
pr_debug("gntdev_vma_open %p\n", vma);
- atomic_inc(&map->users);
+ refcount_inc(&map->users);
}
static void gntdev_vma_close(struct vm_area_struct *vma)
@@ -1004,7 +1005,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
goto unlock_out;
}
- atomic_inc(&map->users);
+ refcount_inc(&map->users);
vma->vm_ops = &gntdev_vmops;