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 --- fs/fuse/file.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 5525a4520b0f..45207a6bb85f 100644 --- 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;