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

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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")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Krzysztof Opasiak 2017-01-19 18:55:28 +01:00 committed by Greg Kroah-Hartman
parent b6092a5715
commit d3acd94c0f
1 changed files with 20 additions and 4 deletions
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24
drivers/usb/gadget/function/f_hid.c
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@ -223,6 +223,13 @@ 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);
@ -238,15 +245,20 @@ 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;
@ -506,14 +518,18 @@ 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);
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)