USB: gadget: detect too-big endpoint 0 requests

commit 153a2d7e3350cc89d406ba2d35be8793a64c2038 upstream.

Sometimes USB hosts can ask for buffers that are too large from endpoint
0, which should not be allowed.  If this happens for OUT requests, stall
the endpoint, but for IN requests, trim the request size to the endpoint
buffer size.

Mot-CRs-fixed: (CR)
CVE-Fixed: CVE-2021-39685
Bug: 210292376

Change-Id: I31c5a748a697b7ff28456b1caee117c2da3378f2
Co-developed-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Gajjala Chakradhar <gajjalac@motorola.com>
Reviewed-on: https://gerrit.mot.com/2197705
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key
(cherry picked from commit 273f9ad1e901701ea311946408128e9651ed42f3)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index ab1340053f3a72e8b43fa2c8d3dd19a168304947..4e47dc05e7686ea020f25806e44b495d640f7718 100644 (file)
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1577,6 +1577,18 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
        struct usb_function             *f = NULL;
        u8                              endp;
 
+       if (w_length > USB_COMP_EP0_BUFSIZ) {
+               if (ctrl->bRequestType == USB_DIR_OUT) {
+                       goto done;
+               } else {
+                       /* Cast away the const, we are going to overwrite on purpose. */
+                       __le16 *temp = (__le16 *)&ctrl->wLength;
+
+                       *temp = cpu_to_le16(USB_COMP_EP0_BUFSIZ);
+                       w_length = USB_COMP_EP0_BUFSIZ;
+               }
+       }
+
        /* partial re-init of the response message; the function or the
         * gadget might need to intercept e.g. a control-OUT completion
         * when we delegate to it.

diff --git a/drivers/usb/gadget/legacy/dbgp.c b/drivers/usb/gadget/legacy/dbgp.c
index 64a77c0fbfd41fea6464d3aad7b35bc6a7ae49ae..f1c5a22704b2814bf0926586851a756ce389f36a 100644 (file)
--- a/drivers/usb/gadget/legacy/dbgp.c
+++ b/drivers/usb/gadget/legacy/dbgp.c
@@ -344,6 +344,19 @@ static int dbgp_setup(struct usb_gadget *gadget,
        void *data = NULL;
        u16 len = 0;
 
+       if (length > DBGP_REQ_LEN) {
+               if (ctrl->bRequestType == USB_DIR_OUT) {
+                       return err;
+               } else {
+                       /* Cast away the const, we are going to overwrite on purpose. */
+                       __le16 *temp = (__le16 *)&ctrl->wLength;
+
+                       *temp = cpu_to_le16(DBGP_REQ_LEN);
+                       length = DBGP_REQ_LEN;
+               }
+       }
+
+
        if (request == USB_REQ_GET_DESCRIPTOR) {
                switch (value>>8) {
                case USB_DT_DEVICE:

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index 5c28bee327e15440210eb33cfb427f7a1fd659b3..8d8b5c86a437454e6961cc0bd152137f591c29a5 100644 (file)
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -113,6 +113,8 @@ enum ep0_state {
 /* enough for the whole queue: most events invalidate others */
 #define        N_EVENT                 5
 
+#define RBUF_SIZE              256
+
 struct dev_data {
        spinlock_t                      lock;
        refcount_t                      count;
@@ -147,7 +149,7 @@ struct dev_data {
        struct dentry                   *dentry;
 
        /* except this scratch i/o buffer for ep0 */
-       u8                              rbuf [256];
+       u8                              rbuf[RBUF_SIZE];
 };
 
 static inline void get_dev (struct dev_data *data)
@@ -1336,6 +1338,18 @@ gadgetfs_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);
 
+       if (w_length > RBUF_SIZE) {
+               if (ctrl->bRequestType == USB_DIR_OUT) {
+                       return value;
+               } else {
+                       /* Cast away the const, we are going to overwrite on purpose. */
+                       __le16 *temp = (__le16 *)&ctrl->wLength;
+
+                       *temp = cpu_to_le16(RBUF_SIZE);
+                       w_length = RBUF_SIZE;
+               }
+       }
+
        spin_lock (&dev->lock);
        dev->setup_abort = 0;
        if (dev->state == STATE_DEV_UNCONNECTED) {