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

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: 99c5150058 ("usb: gadget: hidg: register OUT INT endpoint for SET_REPORT")
Cc: stable@vger.kernel.org
Tested-by: David Lechner <david@lechnology.com>
Bug: 74447444
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>
Change-Id: Ia5d3da0952d87cd82a9e476e90a7cd3633536d94
This commit is contained in:
Krzysztof Opasiak 2017-01-19 18:55:28 +01:00 committed by syphyr
parent 9b5df51027
commit b3de81fb28
1 changed files with 26 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
drivers/usb/gadget/f_hid.c
View File

@ -184,6 +184,12 @@ static struct usb_descriptor_header *hidg_fs_descriptors[] = {
/*-------------------------------------------------------------------------*/
/* Char Device */
static void free_ep_req(struct usb_ep *ep, struct usb_request *req)
{
kfree(req->buf);
usb_ep_free_request(ep, req);
}
static ssize_t f_hidg_read(struct file *file, char __user *buffer,
size_t count, loff_t *ptr)
{
@ -218,6 +224,13 @@ static ssize_t f_hidg_read(struct file *file, char __user *buffer,
/* 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);
@ -233,15 +246,20 @@ static ssize_t f_hidg_read(struct file *file, char __user *buffer,
* 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;
@ -486,6 +504,7 @@ static void hidg_disable(struct usb_function *f)
{
struct f_hidg *hidg = func_to_hidg(f);
struct f_hidg_req_list *list, *next;
unsigned long flags;
usb_ep_disable(hidg->in_ep);
hidg->in_ep->driver_data = NULL;
@ -493,10 +512,13 @@ static void hidg_disable(struct usb_function *f)
usb_ep_disable(hidg->out_ep);
hidg->out_ep->driver_data = NULL;
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)