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Subject[PATCH v2 17/26] usb: gadget: configfs: remove using list iterator after loop body as a ptr
Date
If the list does not contain the expected element, the value of
list_for_each_entry() iterator will not point to a valid structure.
To avoid type confusion in such case, the list iterator
scope will be limited to list_for_each_entry() loop.

In preparation to limiting scope of a list iterator to the list traversal
loop, use a dedicated pointer to point to the found element [1].
Determining if an element was found is then simply checking if
the pointer is != NULL instead of using the potentially bogus pointer.

Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
drivers/usb/gadget/configfs.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index d4a678c0806e..1fb837d9271e 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -418,7 +418,7 @@ static int config_usb_cfg_link(

struct usb_function_instance *fi =
to_usb_function_instance(usb_func_ci);
- struct usb_function_instance *a_fi;
+ struct usb_function_instance *a_fi = NULL, *iter;
struct usb_function *f;
int ret;

@@ -428,11 +428,13 @@ static int config_usb_cfg_link(
* from another gadget or a random directory.
* Also a function instance can only be linked once.
*/
- list_for_each_entry(a_fi, &gi->available_func, cfs_list) {
- if (a_fi == fi)
- break;
+ list_for_each_entry(iter, &gi->available_func, cfs_list) {
+ if (iter != fi)
+ continue;
+ a_fi = iter;
+ break;
}
- if (a_fi != fi) {
+ if (!a_fi) {
ret = -EINVAL;
goto out;
}
@@ -882,15 +884,17 @@ static int os_desc_link(struct config_item *os_desc_ci,
struct gadget_info *gi = os_desc_item_to_gadget_info(os_desc_ci);
struct usb_composite_dev *cdev = &gi->cdev;
struct config_usb_cfg *c_target = to_config_usb_cfg(usb_cfg_ci);
- struct usb_configuration *c;
+ struct usb_configuration *c = NULL, *iter;
int ret;

mutex_lock(&gi->lock);
- list_for_each_entry(c, &cdev->configs, list) {
- if (c == &c_target->c)
- break;
+ list_for_each_entry(iter, &cdev->configs, list) {
+ if (iter != &c_target->c)
+ continue;
+ c = iter;
+ break;
}
- if (c != &c_target->c) {
+ if (!c) {
ret = -EINVAL;
goto out;
}
--
2.25.1
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