Skip to contentSkip to conversation

Patch "usb: gadget: f_hid: fix: Prevent accessing released memory" has been added to the 3.18-stable tree

PATCH [email protected] 1 participant 1 message Apr 3, 2018

Subsystems (2)
Stable branch USB
lore
Share & tools
lore

[email protected]

author maintainer Applied
#0 lore raw

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

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

to the 3.18-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-f_hid-fix-prevent-accessing-released-memory.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From aa65d11aa008f4de58a9cee7e121666d9d68505e Mon Sep 17 00:00:00 2001

From: Krzysztof Opasiak <[email protected]>
Date: Thu, 19 Jan 2017 18:55:28 +0100
Subject: usb: gadget: f_hid: fix: Prevent accessing released memory

From: Krzysztof Opasiak <[email protected]>

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")
Cc [email protected]
Tested-by David Lechner <[email protected]>
Signed-off-by Krzysztof Opasiak <[email protected]>
Signed-off-by Felipe Balbi <[email protected]>
Cc Jerry Zhang <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/usb/gadget/function/f_hid.c |   24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)
drivers/usb/gadget/function/f_hid.c +20 -4
@@ -197,6 +197,13 @@ static ssize_t f_hidg_read(struct file *
 	/* 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);

@@ -212,15 +219,20 @@ static ssize_t f_hidg_read(struct file *
 	 * 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;

@@ -455,6 +467,7 @@ static void hidg_disable(struct usb_func
 {
 	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;

@@ -462,10 +475,13 @@ static void hidg_disable(struct usb_func
 	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)

Patches currently in stable-queue which might be from [email protected] are

queue-3.18/usb-gadget-f_hid-fix-prevent-accessing-released-memory.patch