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, 91 insertions, 0 deletions

diff --git a/include/uapi/mtd/nftl-user.h b/include/uapi/mtd/nftl-user.h
new file mode 100644
index 000000000..b23bdc91c
--- /dev/null
+++ b/include/uapi/mtd/nftl-user.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifndef __MTD_NFTL_USER_H__
+#define __MTD_NFTL_USER_H__
+
+#include <linux/types.h>
+
+/* Block Control Information */
+
+struct nftl_bci {
+	unsigned char ECCSig[6];
+	__u8 Status;
+	__u8 Status1;
+}__attribute__((packed));
+
+/* Unit Control Information */
+
+struct nftl_uci0 {
+	__u16 VirtUnitNum;
+	__u16 ReplUnitNum;
+	__u16 SpareVirtUnitNum;
+	__u16 SpareReplUnitNum;
+} __attribute__((packed));
+
+struct nftl_uci1 {
+	__u32 WearInfo;
+	__u16 EraseMark;
+	__u16 EraseMark1;
+} __attribute__((packed));
+
+struct nftl_uci2 {
+        __u16 FoldMark;
+        __u16 FoldMark1;
+	__u32 unused;
+} __attribute__((packed));
+
+union nftl_uci {
+	struct nftl_uci0 a;
+	struct nftl_uci1 b;
+	struct nftl_uci2 c;
+};
+
+struct nftl_oob {
+	struct nftl_bci b;
+	union nftl_uci u;
+};
+
+/* NFTL Media Header */
+
+struct NFTLMediaHeader {
+	char DataOrgID[6];
+	__u16 NumEraseUnits;
+	__u16 FirstPhysicalEUN;
+	__u32 FormattedSize;
+	unsigned char UnitSizeFactor;
+} __attribute__((packed));
+
+#define MAX_ERASE_ZONES (8192 - 512)
+
+#define ERASE_MARK 0x3c69
+#define SECTOR_FREE 0xff
+#define SECTOR_USED 0x55
+#define SECTOR_IGNORE 0x11
+#define SECTOR_DELETED 0x00
+
+#define FOLD_MARK_IN_PROGRESS 0x5555
+
+#define ZONE_GOOD 0xff
+#define ZONE_BAD_ORIGINAL 0
+#define ZONE_BAD_MARKED 7
+
+
+#endif /* __MTD_NFTL_USER_H__ */