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, 73 insertions, 0 deletions

diff --git a/net/nfc/nci/lib.c b/net/nfc/nci/lib.c
new file mode 100644
index 000000000..473323f80
--- /dev/null
+++ b/net/nfc/nci/lib.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  The NFC Controller Interface is the communication protocol between an
+ *  NFC Controller (NFCC) and a Device Host (DH).
+ *
+ *  Copyright (C) 2011 Texas Instruments, Inc.
+ *
+ *  Written by Ilan Elias <ilane@ti.com>
+ *
+ *  Acknowledgements:
+ *  This file is based on lib.c, which was written
+ *  by Maxim Krasnyansky.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+
+#include <net/nfc/nci.h>
+#include <net/nfc/nci_core.h>
+
+/* NCI status codes to Unix errno mapping */
+int nci_to_errno(__u8 code)
+{
+	switch (code) {
+	case NCI_STATUS_OK:
+		return 0;
+
+	case NCI_STATUS_REJECTED:
+		return -EBUSY;
+
+	case NCI_STATUS_RF_FRAME_CORRUPTED:
+		return -EBADMSG;
+
+	case NCI_STATUS_NOT_INITIALIZED:
+		return -EHOSTDOWN;
+
+	case NCI_STATUS_SYNTAX_ERROR:
+	case NCI_STATUS_SEMANTIC_ERROR:
+	case NCI_STATUS_INVALID_PARAM:
+	case NCI_STATUS_RF_PROTOCOL_ERROR:
+	case NCI_STATUS_NFCEE_PROTOCOL_ERROR:
+		return -EPROTO;
+
+	case NCI_STATUS_UNKNOWN_GID:
+	case NCI_STATUS_UNKNOWN_OID:
+		return -EBADRQC;
+
+	case NCI_STATUS_MESSAGE_SIZE_EXCEEDED:
+		return -EMSGSIZE;
+
+	case NCI_STATUS_DISCOVERY_ALREADY_STARTED:
+		return -EALREADY;
+
+	case NCI_STATUS_DISCOVERY_TARGET_ACTIVATION_FAILED:
+	case NCI_STATUS_NFCEE_INTERFACE_ACTIVATION_FAILED:
+		return -ECONNREFUSED;
+
+	case NCI_STATUS_RF_TRANSMISSION_ERROR:
+	case NCI_STATUS_NFCEE_TRANSMISSION_ERROR:
+		return -ECOMM;
+
+	case NCI_STATUS_RF_TIMEOUT_ERROR:
+	case NCI_STATUS_NFCEE_TIMEOUT_ERROR:
+		return -ETIMEDOUT;
+
+	case NCI_STATUS_FAILED:
+	default:
+		return -ENOSYS;
+	}
+}
+EXPORT_SYMBOL(nci_to_errno);