From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44964 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751710AbeDVN4K (ORCPT ); Sun, 22 Apr 2018 09:56:10 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tuba Yavuz , Felipe Balbi Subject: [PATCH 4.16 040/196] USB: gadget: f_midi: fixing a possible double-free in f_midi Date: Sun, 22 Apr 2018 15:51:00 +0200 Message-Id: <20180422135106.154436732@linuxfoundation.org> In-Reply-To: <20180422135104.278511750@linuxfoundation.org> References: <20180422135104.278511750@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yavuz, Tuba commit 7fafcfdf6377b18b2a726ea554d6e593ba44349f upstream. It looks like there is a possibility of a double-free vulnerability on an error path of the f_midi_set_alt function in the f_midi driver. If the path is feasible then free_ep_req gets called twice: req->complete = f_midi_complete; err = usb_ep_queue(midi->out_ep, req, GFP_ATOMIC); => ... usb_gadget_giveback_request => f_midi_complete (CALLBACK) (inside f_midi_complete, for various cases of status) free_ep_req(ep, req); // first kfree if (err) { ERROR(midi, "%s: couldn't enqueue request: %d\n", midi->out_ep->name, err); free_ep_req(midi->out_ep, req); // second kfree return err; } The double-free possibility was introduced with commit ad0d1a058eac ("usb: gadget: f_midi: fix leak on failed to enqueue out requests"). Found by MOXCAFE tool. Signed-off-by: Tuba Yavuz Fixes: ad0d1a058eac ("usb: gadget: f_midi: fix leak on failed to enqueue out requests") Acked-by: Felipe Balbi Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_midi.c | 3 ++- drivers/usb/gadget/u_f.h | 2 ++ 2 files changed, 4 insertions(+), 1 deletion(-) --- a/drivers/usb/gadget/function/f_midi.c +++ b/drivers/usb/gadget/function/f_midi.c @@ -404,7 +404,8 @@ static int f_midi_set_alt(struct usb_fun if (err) { ERROR(midi, "%s: couldn't enqueue request: %d\n", midi->out_ep->name, err); - free_ep_req(midi->out_ep, req); + if (req->buf != NULL) + free_ep_req(midi->out_ep, req); return err; } } --- a/drivers/usb/gadget/u_f.h +++ b/drivers/usb/gadget/u_f.h @@ -61,7 +61,9 @@ struct usb_request *alloc_ep_req(struct /* Frees a usb_request previously allocated by alloc_ep_req() */ static inline void free_ep_req(struct usb_ep *ep, struct usb_request *req) { + WARN_ON(req->buf == NULL); kfree(req->buf); + req->buf = NULL; usb_ep_free_request(ep, req); }