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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
fs/fuse/file.c | 8 ++++----
fs/fuse/fuse_i.h | 3 ++-
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ec238fb..70770a0 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -58,7 +58,7 @@ struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
}
INIT_LIST_HEAD(&ff->write_entry);
- atomic_set(&ff->count, 1);
+ refcount_set(&ff->count, 1);
RB_CLEAR_NODE(&ff->polled_node);
init_waitqueue_head(&ff->poll_wait);
@@ -77,7 +77,7 @@ void fuse_file_free(struct fuse_file *ff)
static struct fuse_file *fuse_file_get(struct fuse_file *ff)
{
- atomic_inc(&ff->count);
+ refcount_inc(&ff->count);
return ff;
}
@@ -88,7 +88,7 @@ static void fuse_release_end(struct fuse_conn *fc, struct
fuse_req *req)
static void fuse_file_put(struct fuse_file *ff, bool sync)
{
- if (atomic_dec_and_test(&ff->count)) {
+ if (refcount_dec_and_test(&ff->count)) {
struct fuse_req *req = ff->reserved_req;
if (ff->fc->no_open) {
@@ -293,7 +293,7 @@ static int fuse_release(struct inode *inode, struct file
*file)
void fuse_sync_release(struct fuse_file *ff, int flags)
{
- WARN_ON(atomic_read(&ff->count) != 1);
+ WARN_ON(refcount_read(&ff->count) > 1);
fuse_prepare_release(ff, flags, FUSE_RELEASE);
/*
* iput(NULL) is a no-op and since the refcount is 1 and everything's
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 32ac2c9..1d6d67e 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -24,6 +24,7 @@
#include <linux/workqueue.h>
#include <linux/kref.h>
#include <linux/xattr.h>
+#include <linux/refcount.h>
/** Max number of pages that can be used in a single read request */
#define FUSE_MAX_PAGES_PER_REQ 32
@@ -137,7 +138,7 @@ struct fuse_file {
u64 nodeid;
/** Refcount */
- atomic_t count;
+ refcount_t count;
/** FOPEN_* flags returned by open */
u32 open_flags;
--
2.7.4
