This is a note to let you know that I've just added the patch titled
USB: gadget: f_midi: fixing a possible double-free in f_midi
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the usb-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From 7fafcfdf6377b18b2a726ea554d6e593ba44349f Mon Sep 17 00:00:00 2001
From: "Yavuz, Tuba" <tuba@xxxxxxxxxxx>
Date: Fri, 23 Mar 2018 17:00:38 +0000
Subject: 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@xxxxxxxxxxx>
Fixes: ad0d1a058eac ("usb: gadget: f_midi: fix leak on failed to enqueue out requests")
Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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 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);
}
--
2.16.2