fuse: check if copy_file_range() returns larger than requested size

Just like write(), copy_file_range() should check if the return value is
less or equal to the requested number of bytes.

Reported-by: Chunsheng Luo <luochunsheng@ustc.edu>
Closes: https://lore.kernel.org/all/20250807062425.694-1-luochunsheng@ustc.edu/
Fixes: 88bc7d5097a1 ("fuse: add support for copy_file_range()")
Cc: <stable@vger.kernel.org> # v4.20
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 5525a4520b0f89b669c66987379a3afcb8146ea1..45207a6bb85fb667200a0221e2b1a536960d8e74 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3026,6 +3026,9 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
                fc->no_copy_file_range = 1;
                err = -EOPNOTSUPP;
        }
+       if (!err && outarg.size > len)
+               err = -EIO;
+
        if (err)
                goto out;