This is a note to let you know that I've just added the patch titled

usb: gadget: f_hid: fix: Prevent accessing released memory

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: usb-gadget-f_hid-fix-prevent-accessing-released-memory.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From aa65d11aa008f4de58a9cee7e121666d9d68505e Mon Sep 17 00:00:00 2001

From: Krzysztof Opasiak kopasiak90@gmail.com Date: Thu, 19 Jan 2017 18:55:28 +0100 Subject: usb: gadget: f_hid: fix: Prevent accessing released memory

From: Krzysztof Opasiak kopasiak90@gmail.com

commit aa65d11aa008f4de58a9cee7e121666d9d68505e upstream.

When we unlock our spinlock to copy data to user we may get disabled by USB host and free the whole list of completed out requests including the one from which we are copying the data to user memory.

To prevent from this let's remove our working element from the list and place it back only if there is sth left when we finish with it.

Fixes: 99c515005857 ("usb: gadget: hidg: register OUT INT endpoint for SET_REPORT") Cc: stable@vger.kernel.org Tested-by: David Lechner david@lechnology.com Signed-off-by: Krzysztof Opasiak k.opasiak@samsung.com Signed-off-by: Felipe Balbi felipe.balbi@linux.intel.com Cc: Jerry Zhang zhangjerry@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/usb/gadget/function/f_hid.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)

--- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -223,6 +223,13 @@ static ssize_t f_hidg_read(struct file * /* pick the first one */ list = list_first_entry(&hidg->completed_out_req, struct f_hidg_req_list, list); + + /* + * Remove this from list to protect it from beign free() + * while host disables our function + */ + list_del(&list->list); + req = list->req; count = min_t(unsigned int, count, req->actual - list->pos); spin_unlock_irqrestore(&hidg->spinlock, flags); @@ -238,15 +245,20 @@ static ssize_t f_hidg_read(struct file * * call, taking into account its current read position. */ if (list->pos == req->actual) { - spin_lock_irqsave(&hidg->spinlock, flags); - list_del(&list->list); kfree(list); - spin_unlock_irqrestore(&hidg->spinlock, flags);

req->length = hidg->report_length; ret = usb_ep_queue(hidg->out_ep, req, GFP_KERNEL); - if (ret < 0) + if (ret < 0) { + free_ep_req(hidg->out_ep, req); return ret; + } + } else { + spin_lock_irqsave(&hidg->spinlock, flags); + list_add(&list->list, &hidg->completed_out_req); + spin_unlock_irqrestore(&hidg->spinlock, flags); + + wake_up(&hidg->read_queue); }

return count; @@ -490,14 +502,18 @@ static void hidg_disable(struct usb_func { struct f_hidg *hidg = func_to_hidg(f); struct f_hidg_req_list *list, *next; + unsigned long flags;

usb_ep_disable(hidg->in_ep); usb_ep_disable(hidg->out_ep);

+ spin_lock_irqsave(&hidg->spinlock, flags); list_for_each_entry_safe(list, next, &hidg->completed_out_req, list) { + free_ep_req(hidg->out_ep, list->req); list_del(&list->list); kfree(list); } + spin_unlock_irqrestore(&hidg->spinlock, flags); }

static int hidg_set_alt(struct usb_function *f, unsigned intf, unsigned alt)

Patches currently in stable-queue which might be from kopasiak90@gmail.com are

queue-4.4/usb-gadget-f_hid-fix-prevent-accessing-released-memory.patch