+ harden-autofs-ioctl-table.patch added to -mm tree

+ harden-autofs-ioctl-table.patch added to -mm tree

[akpm]

The patch titled
     Subject: autofs: harden ioctl table
has been added to the -mm tree.  Its filename is
     harden-autofs-ioctl-table.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/harden-autofs-ioctl-table.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/harden-autofs-ioctl-table.patch

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------------------------------------------------------
From: Matthew Wilcox <willy@infradead.org>
Subject: autofs: harden ioctl table

The table of ioctl functions should be marked const in order to put them
in read-only memory, and we should use array_index_nospec() to avoid
speculation disclosing the contents of kernel memory to userspace.

Link: https://lkml.kernel.org/r/20200818122203.GO17456@casper.infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/autofs/dev-ioctl.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/autofs/dev-ioctl.c~harden-autofs-ioctl-table
+++ a/fs/autofs/dev-ioctl.c
@@ -8,6 +8,7 @@
 #include <linux/compat.h>
 #include <linux/syscalls.h>
 #include <linux/magic.h>
+#include <linux/nospec.h>
 
 #include "autofs_i.h"
 
@@ -563,7 +564,7 @@ out:
 
 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 {
-	static ioctl_fn _ioctls[] = {
+	static const ioctl_fn _ioctls[] = {
 		autofs_dev_ioctl_version,
 		autofs_dev_ioctl_protover,
 		autofs_dev_ioctl_protosubver,
@@ -581,7 +582,10 @@ static ioctl_fn lookup_dev_ioctl(unsigne
 	};
 	unsigned int idx = cmd_idx(cmd);
 
-	return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
+	if (idx >= ARRAY_SIZE(_ioctls))
+		return NULL;
+	idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls));
+	return _ioctls[idx];
 }
 
 /* ioctl dispatcher */
_

Patches currently in -mm which might be from willy@infradead.org are

mm-debug-do-not-dereference-i_ino-blindly.patch
mm-account-pmd-tables-like-pte-tables.patch
harden-autofs-ioctl-table.patch