From: "Yavuz, Tuba" <[email protected]>
cherry pick from commit 7fafcfdf6377b18b2a726ea554d6e593ba44349f
("USB: gadget: f_midi: fixing a possible double-free in f_midi")
Removing 'return err;' from conflict.
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 <[email protected]>
Fixes: ad0d1a058eac ("usb: gadget: f_midi: fix leak on failed to enqueue out requests")
Acked-by: Felipe Balbi <[email protected]>
Cc: stable <[email protected]> # 4.4.y
---
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 5ead414586a1..e5c4a907e5d4 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -366,7 +366,8 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
if (err) {
ERROR(midi, "%s queue req: %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);
}
}
diff --git a/drivers/usb/gadget/u_f.h b/drivers/usb/gadget/u_f.h
index 69a1d10df04f..3ee365fbc2e2 100644
--- a/drivers/usb/gadget/u_f.h
+++ b/drivers/usb/gadget/u_f.h
@@ -65,7 +65,9 @@ struct usb_request *alloc_ep_req(struct usb_ep *ep, size_t len, int default_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);
}
--
2.23.0.rc1.153.gdeed80330f-goog
On Tue, Aug 20, 2019 at 10:45:13AM -0700, Mark Salyzyn wrote:
> From: "Yavuz, Tuba" <[email protected]>
>
> cherry pick from commit 7fafcfdf6377b18b2a726ea554d6e593ba44349f
> ("USB: gadget: f_midi: fixing a possible double-free in f_midi")
> Removing 'return err;' from conflict.
>
> 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 <[email protected]>
> Fixes: ad0d1a058eac ("usb: gadget: f_midi: fix leak on failed to enqueue out requests")
> Acked-by: Felipe Balbi <[email protected]>
> Cc: stable <[email protected]> # 4.4.y
No signed-off-by from you?
Anyway, this is already in the 4.4.y queue and will be in the next
release.
thanks,
greg k-h
On 8/20/19 1:15 PM, Greg Kroah-Hartman wrote:
> No signed-off-by from you?
>
> Anyway, this is already in the 4.4.y queue and will be in the next
> release.
>
> thanks,
>
> greg k-h
Ok, thanks! I will stand down.
-- Mark