From: Greg Kroah-Hartman gregkh@linuxfoundation.org

mainline inclusion from mainline-v5.16-rc5 commit 153a2d7e3350cc89d406ba2d35be8793a64c2038 category: bugfix bugzilla: NA CVE: CVE-2021-39685

--------------------------------

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.

Co-developed-by: Szymon Heidrich szymon.heidrich@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com Reviewed-by: Xiu Jianfeng xiujianfeng@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/usb/gadget/composite.c | 12 ++++++++++++ drivers/usb/gadget/legacy/dbgp.c | 13 +++++++++++++ drivers/usb/gadget/legacy/inode.c | 16 +++++++++++++++- 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c index af0702cfa92ff..3813249387b3d 100644 --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -1569,6 +1569,18 @@ 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 e1d566c9918ae..e567afcb2794c 100644 --- a/drivers/usb/gadget/legacy/dbgp.c +++ b/drivers/usb/gadget/legacy/dbgp.c @@ -345,6 +345,19 @@ 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 37ca0e669bd85..83fd1b55d497a 100644 --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -109,6 +109,8 @@ 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; @@ -143,7 +145,7 @@ 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) @@ -1332,6 +1334,18 @@ 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) {