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path: root/drivers/usb/gadget/f_fs.c
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Diffstat (limited to 'drivers/usb/gadget/f_fs.c')
-rw-r--r--drivers/usb/gadget/f_fs.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 1222cf9b62d3..34940439bb18 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -753,9 +753,10 @@ static ssize_t ffs_epfile_io(struct file *file,
char __user *buf, size_t len, int read)
{
struct ffs_epfile *epfile = file->private_data;
+ struct usb_gadget *gadget = epfile->ffs->gadget;
struct ffs_ep *ep;
char *data = NULL;
- ssize_t ret;
+ ssize_t ret, data_len;
int halt;
/* Are we still active? */
@@ -788,7 +789,13 @@ static ssize_t ffs_epfile_io(struct file *file,
/* Allocate & copy */
if (!halt) {
- data = kmalloc(len, GFP_KERNEL);
+ /*
+ * Controller may require buffer size to be aligned to
+ * maxpacketsize of an out endpoint.
+ */
+ data_len = read ? usb_ep_align_maybe(gadget, ep->ep, len) : len;
+
+ data = kmalloc(data_len, GFP_KERNEL);
if (unlikely(!data))
return -ENOMEM;
@@ -823,7 +830,7 @@ static ssize_t ffs_epfile_io(struct file *file,
req->context = &done;
req->complete = ffs_epfile_io_complete;
req->buf = data;
- req->length = len;
+ req->length = data_len;
ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
@@ -835,9 +842,17 @@ static ssize_t ffs_epfile_io(struct file *file,
ret = -EINTR;
usb_ep_dequeue(ep->ep, req);
} else {
+ /*
+ * XXX We may end up silently droping data here.
+ * Since data_len (i.e. req->length) may be bigger
+ * than len (after being rounded up to maxpacketsize),
+ * we may end up with more data then user space has
+ * space for.
+ */
ret = ep->status;
if (read && ret > 0 &&
- unlikely(copy_to_user(buf, data, ret)))
+ unlikely(copy_to_user(buf, data,
+ min_t(size_t, ret, len))))
ret = -EFAULT;
}
}