[PATCH] vfs: Don't copy beyond the end of the file

According to `man 2 copy_file_range`, EINVAL should be returned if the
"requested range extends beyond the end of the source file".  Falling
back on do_splice_direct() will return 0 in this case, so let's add an
explicit check to match the behavior documented in the man page.

Signed-off-by: Anna Schumaker <redacted>
---
 fs/read_write.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/read_write.c b/fs/read_write.c
index 66215a7..1cbab4e 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c

@@ -1497,6 +1497,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (unlikely(ret))
 		return ret;
 
+	if (pos_in >= i_size_read(inode_in))
+		return -EINVAL;
+
 	if (!(file_in->f_mode & FMODE_READ) ||
 	    !(file_out->f_mode & FMODE_WRITE) ||
 	    (file_out->f_flags & O_APPEND))

-- 
2.9.3