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usb: gadget: composite: remove check of list iterator against head past the loop body 

When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limiting the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220308171818.384491-22-jakobkoschel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jakob Koschel 2022-03-08 18:18:13 +01:00 committed by Greg Kroah-Hartman
parent 418947745c
commit eb6dc99ea2
1 changed files with 5 additions and 4 deletions
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9
drivers/usb/gadget/composite.c
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@ -1690,6 +1690,7 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
u16 w_value = le16_to_cpu(ctrl->wValue);
u16 w_length = le16_to_cpu(ctrl->wLength);
struct usb_function *f = NULL;
struct usb_function *iter;
u8 endp;
if (w_length > USB_COMP_EP0_BUFSIZ) {
@ -2046,12 +2047,12 @@ unknown:
if (!cdev->config)
break;
endp = ((w_index & 0x80) >> 3) | (w_index & 0x0f);
list_for_each_entry(f, &cdev->config->functions, list) {
if (test_bit(endp, f->endpoints))
list_for_each_entry(iter, &cdev->config->functions, list) {
if (test_bit(endp, iter->endpoints)) {
f = iter;
break;
}
}
if (&f->list == &cdev->config->functions)
f = NULL;
break;
}
try_fun_setup: