Patch "usb: gadget: configfs: remove using list iterator after loop body as a ptr" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    usb: gadget: configfs: remove using list iterator after loop body as a ptr

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-gadget-configfs-remove-using-list-iterator-after.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 53427a05758913b2d6f644b8a22e9a82eb64bf9c
Author: Jakob Koschel <jakobkoschel@xxxxxxxxx>
Date:   Tue Mar 8 18:18:09 2022 +0100

    usb: gadget: configfs: remove using list iterator after loop body as a ptr
    
    [ Upstream commit 36f4c25ce32ed8a2e6304ebee6246b7f0b3b9a6f ]
    
    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@xxxxxxxxx/
    Signed-off-by: Jakob Koschel <jakobkoschel@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20220308171818.384491-18-jakobkoschel@xxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Stable-dep-of: 89e7252d6c7e ("usb: gadget: configfs: Restrict symlink creation is UDC already binded")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 8166e771e8663..891d8e4023221 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;
 	}
@@ -889,15 +891,17 @@ static int os_desc_link(struct config_item *os_desc_ci,
 					struct gadget_info, os_desc_group);
 	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;
 	}