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authorLars-Peter Clausen <lars@metafoo.de>2016-03-30 13:49:14 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-01 12:15:51 -0700
commited97f0d96dfad18989b922c4c4095e9d06230bf6 (patch)
treee825e71a56371e1fd2a1a05e0e3240e46f10c662 /drivers
parent92f54c192b643da15504bc022dd6f17c2f930266 (diff)
usb: gadget: f_fs: Fix EFAULT generation for async read operations
commit 332a5b446b7916d272c2a659a3b20909ce34d2c1 upstream. 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/gadget/function/f_fs.c2
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 79d895c2dd71..97ef75af9632 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);
}