cdrom: Make device operations read-only
Since function tables are a common target for attackers, it's best to keep
them in read-only memory. As such, this makes the CDROM device ops tables
const. This drops additionally n_minors, since it isn't used meaningfully,
and sets the only user of cdrom_dummy_generic_packet explicitly so the
variables can all be const.
Inspired by similar changes in grsecurity/PaX.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/Documentation/cdrom/cdrom-standard.tex b/Documentation/cdrom/cdrom-standard.tex
index c06233f..8f85b0e 100644
--- a/Documentation/cdrom/cdrom-standard.tex
+++ b/Documentation/cdrom/cdrom-standard.tex
@@ -249,7 +249,6 @@
unsigned\ long);\cr
\noalign{\medskip}
&const\ int& capability;& capability flags \cr
- &int& n_minors;& number of active minor devices \cr
\};\cr
}
$$
@@ -258,13 +257,7 @@
function is not implemented, however, this $struct$ should contain a
NULL instead. The $capability$ flags specify the capabilities of the
\cdrom\ hardware and/or low-level \cdrom\ driver when a \cdrom\ drive
-is registered with the \UCD. The value $n_minors$ should be a positive
-value indicating the number of minor devices that are supported by
-the low-level device driver, normally~1. Although these two variables
-are `informative' rather than `operational,' they are included in
-$cdrom_device_ops$ because they describe the capability of the {\em
-driver\/} rather than the {\em drive}. Nomenclature has always been
-difficult in computer programming.
+is registered with the \UCD.
Note that most functions have fewer parameters than their
$blkdev_fops$ counterparts. This is because very little of the