diff options
| author | Lars-Peter Clausen <lars@metafoo.de> | 2016-03-30 13:49:14 +0200 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-07-10 23:07:26 -0400 |
| commit | 4b6986fcceb200b2edd97d7cc5799d8a7ae53086 (patch) | |
| tree | 60b2f7c618146cf649561768475120d252aca6d7 | |
| parent | 616ffbf1a53617037e2e46d2f40232a5cb1ea8c0 (diff) | |
usb: gadget: f_fs: Fix EFAULT generation for async read operations
[ Upstream commit 332a5b446b7916d272c2a659a3b20909ce34d2c1 ]
In the current implementation functionfs generates a EFAULT for async read
operations if the read buffer size is larger than the URB data size. Since
a application does not necessarily know how much data the host side is
going to send it typically supplies a buffer larger than the actual data,
which will then result in a EFAULT error.
This behaviour was introduced while refactoring the code to use iov_iter
interface in commit c993c39b8639 ("gadget/function/f_fs.c: use put iov_iter
into io_data"). The original code took the minimum over the URB size and
the user buffer size and then attempted to copy that many bytes using
copy_to_user(). If copy_to_user() could not copy all data a EFAULT error
was generated. Restore the original behaviour by only generating a EFAULT
error when the number of bytes copied is not the size of the URB and the
target buffer has not been fully filled.
Commit 342f39a6c8d3 ("usb: gadget: f_fs: fix check in read operation")
already fixed the same problem for the synchronous read path.
Fixes: c993c39b8639 ("gadget/function/f_fs.c: use put iov_iter into io_data")
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
| -rw-r--r-- | drivers/usb/gadget/function/f_fs.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 82240dbdf6dd..db9433eed2cc 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -651,7 +651,7 @@ static void ffs_user_copy_worker(struct work_struct *work) if (io_data->read && ret > 0) { use_mm(io_data->mm); ret = copy_to_iter(io_data->buf, ret, &io_data->data); - if (iov_iter_count(&io_data->data)) + if (ret != io_data->req->actual && iov_iter_count(&io_data->data)) ret = -EFAULT; unuse_mm(io_data->mm); } |