1 files changed, 42 insertions, 14 deletions

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 25ad1e97a458..1922fd02043c 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -1711,16 +1711,24 @@ static void ffs_data_put(struct ffs_data *ffs)
 
 static void ffs_data_closed(struct ffs_data *ffs)
 {
+	struct ffs_epfile *epfiles;
+	unsigned long flags;
+
 	ENTER();
 
 	if (atomic_dec_and_test(&ffs->opened)) {
 		if (ffs->no_disconnect) {
 			ffs->state = FFS_DEACTIVATED;
-			if (ffs->epfiles) {
-				ffs_epfiles_destroy(ffs->epfiles,
-						   ffs->eps_count);
-				ffs->epfiles = NULL;
-			}
+			spin_lock_irqsave(&ffs->eps_lock, flags);
+			epfiles = ffs->epfiles;
+			ffs->epfiles = NULL;
+			spin_unlock_irqrestore(&ffs->eps_lock,
+							flags);
+
+			if (epfiles)
+				ffs_epfiles_destroy(epfiles,
+						 ffs->eps_count);
+
 			if (ffs->setup_state == FFS_SETUP_PENDING)
 				__ffs_ep0_stall(ffs);
 		} else {
@@ -1767,14 +1775,27 @@ static struct ffs_data *ffs_data_new(const char *dev_name)
 
 static void ffs_data_clear(struct ffs_data *ffs)
 {
+	struct ffs_epfile *epfiles;
+	unsigned long flags;
+
 	ENTER();
 
 	ffs_closed(ffs);
 
 	BUG_ON(ffs->gadget);
 
-	if (ffs->epfiles) {
-		ffs_epfiles_destroy(ffs->epfiles, ffs->eps_count);
+	spin_lock_irqsave(&ffs->eps_lock, flags);
+	epfiles = ffs->epfiles;
+	ffs->epfiles = NULL;
+	spin_unlock_irqrestore(&ffs->eps_lock, flags);
+
+	/*
+	 * potential race possible between ffs_func_eps_disable
+	 * & ffs_epfile_release therefore maintaining a local
+	 * copy of epfile will save us from use-after-free.
+	 */
+	if (epfiles) {
+		ffs_epfiles_destroy(epfiles, ffs->eps_count);
 		ffs->epfiles = NULL;
 	}
 
@@ -1922,12 +1943,15 @@ static void ffs_epfiles_destroy(struct ffs_epfile *epfiles, unsigned count)
 
 static void ffs_func_eps_disable(struct ffs_function *func)
 {
-	struct ffs_ep *ep         = func->eps;
-	struct ffs_epfile *epfile = func->ffs->epfiles;
-	unsigned count            = func->ffs->eps_count;
+	struct ffs_ep *ep;
+	struct ffs_epfile *epfile;
+	unsigned short count;
 	unsigned long flags;
 
 	spin_lock_irqsave(&func->ffs->eps_lock, flags);
+	count = func->ffs->eps_count;
+	epfile = func->ffs->epfiles;
+	ep = func->eps;
 	while (count--) {
 		/* pending requests get nuked */
 		if (ep->ep)
@@ -1945,14 +1969,18 @@ static void ffs_func_eps_disable(struct ffs_function *func)
 
 static int ffs_func_eps_enable(struct ffs_function *func)
 {
-	struct ffs_data *ffs      = func->ffs;
-	struct ffs_ep *ep         = func->eps;
-	struct ffs_epfile *epfile = ffs->epfiles;
-	unsigned count            = ffs->eps_count;
+	struct ffs_data *ffs;
+	struct ffs_ep *ep;
+	struct ffs_epfile *epfile;
+	unsigned short count;
 	unsigned long flags;
 	int ret = 0;
 
 	spin_lock_irqsave(&func->ffs->eps_lock, flags);
+	ffs = func->ffs;
+	ep = func->eps;
+	epfile = ffs->epfiles;
+	count = ffs->eps_count;
 	while(count--) {
 		ep->ep->driver_data = ep;