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fuse: convert fuse_conn.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>
This commit is contained in:
Elena Reshetova 2017-03-03 11:04:05 +02:00 committed by Miklos Szeredi
parent ec99f6d31f
commit 095fc40ace
2 changed files with 4 additions and 4 deletions
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2
fs/fuse/fuse_i.h
View File

@ -449,7 +449,7 @@ struct fuse_conn {
spinlock_t lock; spinlock_t lock;
/** Refcount */ /** Refcount */
atomic_t count; refcount_t count;
/** Number of fuse_dev's */ /** Number of fuse_dev's */
atomic_t dev_count; atomic_t dev_count;

6
fs/fuse/inode.c
View File

@ -608,7 +608,7 @@ void fuse_conn_init(struct fuse_conn *fc)
memset(fc, 0, sizeof(*fc)); memset(fc, 0, sizeof(*fc));
spin_lock_init(&fc->lock); spin_lock_init(&fc->lock);
init_rwsem(&fc->killsb); init_rwsem(&fc->killsb);
atomic_set(&fc->count, 1); refcount_set(&fc->count, 1);
atomic_set(&fc->dev_count, 1); atomic_set(&fc->dev_count, 1);
init_waitqueue_head(&fc->blocked_waitq); init_waitqueue_head(&fc->blocked_waitq);
init_waitqueue_head(&fc->reserved_req_waitq); init_waitqueue_head(&fc->reserved_req_waitq);
@ -631,7 +631,7 @@ EXPORT_SYMBOL_GPL(fuse_conn_init);
void fuse_conn_put(struct fuse_conn *fc) void fuse_conn_put(struct fuse_conn *fc)
{ {
if (atomic_dec_and_test(&fc->count)) { if (refcount_dec_and_test(&fc->count)) {
if (fc->destroy_req) if (fc->destroy_req)
fuse_request_free(fc->destroy_req); fuse_request_free(fc->destroy_req);
fc->release(fc); fc->release(fc);
@ -641,7 +641,7 @@ EXPORT_SYMBOL_GPL(fuse_conn_put);
struct fuse_conn *fuse_conn_get(struct fuse_conn *fc) struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
{ {
atomic_inc(&fc->count); refcount_inc(&fc->count);
return fc; return fc;
} }
EXPORT_SYMBOL_GPL(fuse_conn_get); EXPORT_SYMBOL_GPL(fuse_conn_get);