openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 148 insertions, 0 deletions

diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c
new file mode 100644
index 000000000..a5b60778b
--- /dev/null
+++ b/fs/gfs2/acl.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/buffer_head.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/gfs2_ondisk.h>
+
+#include "gfs2.h"
+#include "incore.h"
+#include "acl.h"
+#include "xattr.h"
+#include "glock.h"
+#include "inode.h"
+#include "meta_io.h"
+#include "quota.h"
+#include "rgrp.h"
+#include "trans.h"
+#include "util.h"
+
+static const char *gfs2_acl_name(int type)
+{
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		return XATTR_POSIX_ACL_ACCESS;
+	case ACL_TYPE_DEFAULT:
+		return XATTR_POSIX_ACL_DEFAULT;
+	}
+	return NULL;
+}
+
+static struct posix_acl *__gfs2_get_acl(struct inode *inode, int type)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct posix_acl *acl;
+	const char *name;
+	char *data;
+	int len;
+
+	if (!ip->i_eattr)
+		return NULL;
+
+	name = gfs2_acl_name(type);
+	len = gfs2_xattr_acl_get(ip, name, &data);
+	if (len <= 0)
+		return ERR_PTR(len);
+	acl = posix_acl_from_xattr(&init_user_ns, data, len);
+	kfree(data);
+	return acl;
+}
+
+struct posix_acl *gfs2_get_acl(struct inode *inode, int type, bool rcu)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	bool need_unlock = false;
+	struct posix_acl *acl;
+
+	if (rcu)
+		return ERR_PTR(-ECHILD);
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		int ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
+					     LM_FLAG_ANY, &gh);
+		if (ret)
+			return ERR_PTR(ret);
+		need_unlock = true;
+	}
+	acl = __gfs2_get_acl(inode, type);
+	if (need_unlock)
+		gfs2_glock_dq_uninit(&gh);
+	return acl;
+}
+
+int __gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	int error;
+	size_t len = 0;
+	char *data = NULL;
+	const char *name = gfs2_acl_name(type);
+
+	if (acl) {
+		data = posix_acl_to_xattr(&init_user_ns, acl, &len, GFP_NOFS);
+		if (data == NULL)
+			return -ENOMEM;
+	}
+
+	error = __gfs2_xattr_set(inode, name, data, len, 0, GFS2_EATYPE_SYS);
+	if (error)
+		goto out;
+	set_cached_acl(inode, type, acl);
+out:
+	kfree(data);
+	return error;
+}
+
+int gfs2_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+		 struct posix_acl *acl, int type)
+{
+	struct inode *inode = d_inode(dentry);
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	bool need_unlock = false;
+	int ret;
+	umode_t mode;
+
+	if (acl && acl->a_count > GFS2_ACL_MAX_ENTRIES(GFS2_SB(inode)))
+		return -E2BIG;
+
+	ret = gfs2_qa_get(ip);
+	if (ret)
+		return ret;
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
+		if (ret)
+			goto out;
+		need_unlock = true;
+	}
+
+	mode = inode->i_mode;
+	if (type == ACL_TYPE_ACCESS && acl) {
+		ret = posix_acl_update_mode(&nop_mnt_idmap, inode, &mode, &acl);
+		if (ret)
+			goto unlock;
+	}
+
+	ret = __gfs2_set_acl(inode, acl, type);
+	if (!ret && mode != inode->i_mode) {
+		inode_set_ctime_current(inode);
+		inode->i_mode = mode;
+		mark_inode_dirty(inode);
+	}
+unlock:
+	if (need_unlock)
+		gfs2_glock_dq_uninit(&gh);
+out:
+	gfs2_qa_put(ip);
+	return ret;
+}