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authorElena Reshetova <elena.reshetova@intel.com>2017-03-06 16:20:50 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-03-23 13:57:19 +0100
commitf7d88d24c5a2b66b02770e2776fce72b5fd70193 (patch)
tree97b3f2f75da7998195f1344a2438fc3079ca57a5 /drivers/char/mspec.c
parent132c93d4215c5ea12f8bb291249ede159d507b6e (diff)
drivers, char: convert vma_data.refcnt 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char/mspec.c')
-rw-r--r--drivers/char/mspec.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
index a9c2fa3c81e5..7b75669d3670 100644
--- a/drivers/char/mspec.c
+++ b/drivers/char/mspec.c
@@ -43,6 +43,7 @@
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/numa.h>
+#include <linux/refcount.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <linux/atomic.h>
@@ -89,7 +90,7 @@ static int is_sn2;
* protect in fork case where multiple tasks share the vma_data.
*/
struct vma_data {
- atomic_t refcnt; /* Number of vmas sharing the data. */
+ refcount_t refcnt; /* Number of vmas sharing the data. */
spinlock_t lock; /* Serialize access to this structure. */
int count; /* Number of pages allocated. */
enum mspec_page_type type; /* Type of pages allocated. */
@@ -144,7 +145,7 @@ mspec_open(struct vm_area_struct *vma)
struct vma_data *vdata;
vdata = vma->vm_private_data;
- atomic_inc(&vdata->refcnt);
+ refcount_inc(&vdata->refcnt);
}
/*
@@ -162,7 +163,7 @@ mspec_close(struct vm_area_struct *vma)
vdata = vma->vm_private_data;
- if (!atomic_dec_and_test(&vdata->refcnt))
+ if (!refcount_dec_and_test(&vdata->refcnt))
return;
last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
@@ -274,7 +275,7 @@ mspec_mmap(struct file *file, struct vm_area_struct *vma,
vdata->vm_end = vma->vm_end;
vdata->type = type;
spin_lock_init(&vdata->lock);
- atomic_set(&vdata->refcnt, 1);
+ refcount_set(&vdata->refcnt, 1);
vma->vm_private_data = vdata;
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;