From: Michal Nazarewicz <mina86@xxxxxxxxxx>
Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
to be aligned to maxpacketsize of an out endpoint. ffs_epfile_io() needs
to pad epout buffer to match above condition if quirk is found.
Signed-off-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
---
I'm wondering whether the len should be aligned down rather then up.
This would have it's own problems, but maybe better then
a possibility of silently dropping data.
drivers/usb/gadget/f_fs.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index f875f26..ea0b8ba 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -753,8 +753,9 @@ 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;
- ssize_t ret;
+ ssize_t ret, data_len;
char *data;
int halt;
@@ -787,6 +788,13 @@ static ssize_t ffs_epfile_io(struct file *file,
/* Allocate & copy */
if (!halt) {
+ /*
+ * Controller requires buffer size to be aligned to
+ * maxpacketsize of an out endpoint.
+ */
+ data_len = read && gadget->quirk_ep_out_aligned_size ?
+ usb_ep_align_maxpacketsize(ep->ep, len) : len;
+
data = kmalloc(len, GFP_KERNEL);
if (unlikely(!data))
return -ENOMEM;
@@ -824,7 +832,7 @@ 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);
@@ -836,9 +844,16 @@ 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(ret, len))))
ret = -EFAULT;
}
}
--
1.8.3.2
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