usb: gadget: f_fs: Fix EFAULT generation for async read operations
[ Upstream commit332a5b446b
] 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 commitc993c39b86
("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. Commit342f39a6c8
("usb: gadget: f_fs: fix check in read operation") already fixed the same problem for the synchronous read path. Fixes:c993c39b86
("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>
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@ -651,7 +651,7 @@ static void ffs_user_copy_worker(struct work_struct *work)
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if (io_data->read && ret > 0) {
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if (io_data->read && ret > 0) {
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use_mm(io_data->mm);
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use_mm(io_data->mm);
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ret = copy_to_iter(io_data->buf, ret, &io_data->data);
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ret = copy_to_iter(io_data->buf, ret, &io_data->data);
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if (iov_iter_count(&io_data->data))
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if (ret != io_data->req->actual && iov_iter_count(&io_data->data))
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ret = -EFAULT;
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ret = -EFAULT;
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unuse_mm(io_data->mm);
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unuse_mm(io_data->mm);
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}
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}
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