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authorElena Reshetova <elena.reshetova@intel.com>2017-03-03 11:04:04 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2017-04-18 16:58:37 +0200
commitec99f6d31f2590a4c0ff2dae8fb1fa27f0647a42 (patch)
tree21d44ad6c09ba6799248e53fe85596a3a6d2596e
parent4e8c2eb54327a6f8b0ef6d6afb28ab24b721dbe0 (diff)
fuse: convert fuse_req.count 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: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/fuse/dev.c9
-rw-r--r--fs/fuse/fuse_i.h2
2 files changed, 5 insertions, 6 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index b681b43c766e..5e815072be1b 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -45,7 +45,7 @@ static void fuse_request_init(struct fuse_req *req, struct page **pages,
INIT_LIST_HEAD(&req->list);
INIT_LIST_HEAD(&req->intr_entry);
init_waitqueue_head(&req->waitq);
- atomic_set(&req->count, 1);
+ refcount_set(&req->count, 1);
req->pages = pages;
req->page_descs = page_descs;
req->max_pages = npages;
@@ -102,14 +102,13 @@ void fuse_request_free(struct fuse_req *req)
void __fuse_get_request(struct fuse_req *req)
{
- atomic_inc(&req->count);
+ refcount_inc(&req->count);
}
/* Must be called with > 1 refcount */
static void __fuse_put_request(struct fuse_req *req)
{
- BUG_ON(atomic_read(&req->count) < 2);
- atomic_dec(&req->count);
+ refcount_dec(&req->count);
}
static void fuse_req_init_context(struct fuse_req *req)
@@ -264,7 +263,7 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
{
- if (atomic_dec_and_test(&req->count)) {
+ if (refcount_dec_and_test(&req->count)) {
if (test_bit(FR_BACKGROUND, &req->flags)) {
/*
* We get here in the unlikely case that a background
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 1d6d67e64f49..9d4374032290 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -307,7 +307,7 @@ struct fuse_req {
struct list_head intr_entry;
/** refcount */
- atomic_t count;
+ refcount_t count;
/** Unique ID for the interrupt request */
u64 intr_unique;