Commit 76c94651 authored Jan 29, 2022 by Jordy Zomer Committed by Greg Kroah-Hartman Apr 20, 2022

dm ioctl: prevent potential spectre v1 gadget



[ Upstream commit cd9c88da171a62c4b0f1c70e50c75845969fbc18 ]

It appears like cmd could be a Spectre v1 gadget as it's supplied by a
user and used as an array index. Prevent the contents of kernel memory
from being leaked to userspace via speculative execution by using
array_index_nospec.

Signed-off-by: Jordy Zomer <jordy@pwning.systems>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent ffa0495a

drivers/md/dm-ioctl.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@
		#include <linux/dm-ioctl.h>
		#include <linux/hdreg.h>
		#include <linux/compat.h>
		#include <linux/nospec.h>

		#include <asm/uaccess.h>

		@@ -1642,6 +1643,7 @@ static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
		if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
		return NULL;

		cmd = array_index_nospec(cmd, ARRAY_SIZE(_ioctls));
		*ioctl_flags = _ioctls[cmd].flags;
		return _ioctls[cmd].fn;
		}