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, 134 insertions, 0 deletions

diff --git a/drivers/memory/pl353-smc.c b/drivers/memory/pl353-smc.c
new file mode 100644
index 000000000..28a8cc560
--- /dev/null
+++ b/drivers/memory/pl353-smc.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM PL353 SMC driver
+ *
+ * Copyright (C) 2012 - 2018 Xilinx, Inc
+ * Author: Punnaiah Choudary Kalluri <punnaiah@xilinx.com>
+ * Author: Naga Sureshkumar Relli <nagasure@xilinx.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/amba/bus.h>
+
+/**
+ * struct pl353_smc_data - Private smc driver structure
+ * @memclk:		Pointer to the peripheral clock
+ * @aclk:		Pointer to the AXI peripheral clock
+ */
+struct pl353_smc_data {
+	struct clk		*memclk;
+	struct clk		*aclk;
+};
+
+static int __maybe_unused pl353_smc_suspend(struct device *dev)
+{
+	struct pl353_smc_data *pl353_smc = dev_get_drvdata(dev);
+
+	clk_disable(pl353_smc->memclk);
+	clk_disable(pl353_smc->aclk);
+
+	return 0;
+}
+
+static int __maybe_unused pl353_smc_resume(struct device *dev)
+{
+	struct pl353_smc_data *pl353_smc = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_enable(pl353_smc->aclk);
+	if (ret) {
+		dev_err(dev, "Cannot enable axi domain clock.\n");
+		return ret;
+	}
+
+	ret = clk_enable(pl353_smc->memclk);
+	if (ret) {
+		dev_err(dev, "Cannot enable memory clock.\n");
+		clk_disable(pl353_smc->aclk);
+		return ret;
+	}
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(pl353_smc_dev_pm_ops, pl353_smc_suspend,
+			 pl353_smc_resume);
+
+static const struct of_device_id pl353_smc_supported_children[] = {
+	{
+		.compatible = "cfi-flash"
+	},
+	{
+		.compatible = "arm,pl353-nand-r2p1",
+	},
+	{}
+};
+
+static int pl353_smc_probe(struct amba_device *adev, const struct amba_id *id)
+{
+	struct device_node *of_node = adev->dev.of_node;
+	const struct of_device_id *match = NULL;
+	struct pl353_smc_data *pl353_smc;
+
+	pl353_smc = devm_kzalloc(&adev->dev, sizeof(*pl353_smc), GFP_KERNEL);
+	if (!pl353_smc)
+		return -ENOMEM;
+
+	pl353_smc->aclk = devm_clk_get_enabled(&adev->dev, "apb_pclk");
+	if (IS_ERR(pl353_smc->aclk))
+		return dev_err_probe(&adev->dev, PTR_ERR(pl353_smc->aclk),
+				     "aclk clock not found.\n");
+
+	pl353_smc->memclk = devm_clk_get_enabled(&adev->dev, "memclk");
+	if (IS_ERR(pl353_smc->memclk))
+		return dev_err_probe(&adev->dev, PTR_ERR(pl353_smc->memclk),
+				     "memclk clock not found.\n");
+
+	amba_set_drvdata(adev, pl353_smc);
+
+	/* Find compatible children. Only a single child is supported */
+	for_each_available_child_of_node_scoped(of_node, child) {
+		match = of_match_node(pl353_smc_supported_children, child);
+		if (!match) {
+			dev_warn(&adev->dev, "unsupported child node\n");
+			continue;
+		}
+		of_platform_device_create(child, NULL, &adev->dev);
+		break;
+	}
+	if (!match) {
+		dev_err(&adev->dev, "no matching children\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static const struct amba_id pl353_ids[] = {
+	{
+		.id = 0x00041353,
+		.mask = 0x000fffff,
+	},
+	{ 0, 0 },
+};
+MODULE_DEVICE_TABLE(amba, pl353_ids);
+
+static struct amba_driver pl353_smc_driver = {
+	.drv = {
+		.name = "pl353-smc",
+		.pm = &pl353_smc_dev_pm_ops,
+	},
+	.id_table = pl353_ids,
+	.probe = pl353_smc_probe,
+};
+
+module_amba_driver(pl353_smc_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("ARM PL353 SMC Driver");
+MODULE_LICENSE("GPL");