From 96dc465173a1f790e805246206aee3d18770f614 Mon Sep 17 00:00:00 2001 From: "Yavuz, Tuba" Date: Fri, 23 Mar 2018 17:00:38 +0000 Subject: [PATCH] USB: gadget: f_midi: fixing a possible double-free in f_midi 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(-) diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c index 5d3d794..71cf552 100644 --- a/drivers/usb/gadget/function/f_midi.c +++ b/drivers/usb/gadget/function/f_midi.c @@ -405,7 +405,8 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt) 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; } } diff --git a/drivers/usb/gadget/u_f.h b/drivers/usb/gadget/u_f.h index 7d53a47..2f03334 100644 --- a/drivers/usb/gadget/u_f.h +++ b/drivers/usb/gadget/u_f.h @@ -64,7 +64,9 @@ struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len); /* 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); } -- 2.7.4