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Lars-Peter Clausen authored
commit 332a5b44 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 c993c39b ("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 342f39a6 ("usb: gadget: f_fs: fix check in read operation") already fixed the same problem for the synchronous read path. Fixes: c993c39b ("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: Kamal Mostafa <kamal@canonical.com>
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