diff mbox series

[144/156] autofs: harden ioctl table

Message ID 20201016025003.otAbjz8xU%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [001/156] device-dax/kmem: fix resource release | expand

Commit Message

Andrew Morton Oct. 16, 2020, 2:50 a.m. UTC
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(-)
diff mbox series

Patch

--- 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 */