The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 7fafcfdf6377b18b2a726ea554d6e593ba44349f Mon Sep 17 00:00:00 2001
From: "Yavuz, Tuba" tuba@ece.ufl.edu Date: Fri, 23 Mar 2018 17:00:38 +0000 Subject: [PATCH] USB: gadget: f_midi: fixing a possible double-free in f_midi
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 tuba@ece.ufl.edu Fixes: ad0d1a058eac ("usb: gadget: f_midi: fix leak on failed to enqueue out requests") Acked-by: Felipe Balbi felipe.balbi@linux.intel.com Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c index 4eb96b91cc40..e8f35db42394 100644 --- 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_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 c3fbef2bb5db..09f90447fed5 100644 --- 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 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); }