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, 250 insertions, 0 deletions

diff --git a/drivers/clk/clk-bulk.c b/drivers/clk/clk-bulk.c
new file mode 100644
index 000000000..acd9dff30
--- /dev/null
+++ b/drivers/clk/clk-bulk.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2017 NXP
+ *
+ * Dong Aisheng <aisheng.dong@nxp.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+static int __must_check of_clk_bulk_get(struct device *dev,
+					struct device_node *np, int num_clks,
+					struct clk_bulk_data *clks)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_clks; i++) {
+		clks[i].id = NULL;
+		clks[i].clk = NULL;
+	}
+
+	for (i = 0; i < num_clks; i++) {
+		of_property_read_string_index(np, "clock-names", i, &clks[i].id);
+		clks[i].clk = of_clk_get(np, i);
+		if (IS_ERR(clks[i].clk)) {
+			ret = PTR_ERR(clks[i].clk);
+			dev_err_probe(dev, ret, "%pOF: Failed to get clk index: %d (%s)\n",
+				      np, i, clks[i].id);
+			clks[i].clk = NULL;
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	clk_bulk_put(i, clks);
+
+	return ret;
+}
+
+static int __must_check of_clk_bulk_get_all(struct device *dev,
+					    struct device_node *np,
+					    struct clk_bulk_data **clks)
+{
+	struct clk_bulk_data *clk_bulk;
+	int num_clks;
+	int ret;
+
+	num_clks = of_clk_get_parent_count(np);
+	if (!num_clks)
+		return 0;
+
+	clk_bulk = kmalloc_objs(*clk_bulk, num_clks);
+	if (!clk_bulk)
+		return -ENOMEM;
+
+	ret = of_clk_bulk_get(dev, np, num_clks, clk_bulk);
+	if (ret) {
+		kfree(clk_bulk);
+		return ret;
+	}
+
+	*clks = clk_bulk;
+
+	return num_clks;
+}
+
+void clk_bulk_put(int num_clks, struct clk_bulk_data *clks)
+{
+	while (--num_clks >= 0) {
+		clk_put(clks[num_clks].clk);
+		clks[num_clks].clk = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(clk_bulk_put);
+
+static int __clk_bulk_get(struct device *dev, int num_clks,
+			  struct clk_bulk_data *clks, bool optional)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_clks; i++)
+		clks[i].clk = NULL;
+
+	for (i = 0; i < num_clks; i++) {
+		clks[i].clk = clk_get(dev, clks[i].id);
+		if (IS_ERR(clks[i].clk)) {
+			ret = PTR_ERR(clks[i].clk);
+			clks[i].clk = NULL;
+
+			if (ret == -ENOENT && optional)
+				continue;
+
+			dev_err_probe(dev, ret,
+				      "Failed to get clk '%s'\n",
+				      clks[i].id);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	clk_bulk_put(i, clks);
+
+	return ret;
+}
+
+int __must_check clk_bulk_get(struct device *dev, int num_clks,
+			      struct clk_bulk_data *clks)
+{
+	return __clk_bulk_get(dev, num_clks, clks, false);
+}
+EXPORT_SYMBOL(clk_bulk_get);
+
+int __must_check clk_bulk_get_optional(struct device *dev, int num_clks,
+				       struct clk_bulk_data *clks)
+{
+	return __clk_bulk_get(dev, num_clks, clks, true);
+}
+EXPORT_SYMBOL_GPL(clk_bulk_get_optional);
+
+void clk_bulk_put_all(int num_clks, struct clk_bulk_data *clks)
+{
+	if (IS_ERR_OR_NULL(clks))
+		return;
+
+	clk_bulk_put(num_clks, clks);
+
+	kfree(clks);
+}
+EXPORT_SYMBOL(clk_bulk_put_all);
+
+int __must_check clk_bulk_get_all(struct device *dev,
+				  struct clk_bulk_data **clks)
+{
+	struct device_node *np = dev_of_node(dev);
+
+	if (!np)
+		return 0;
+
+	return of_clk_bulk_get_all(dev, np, clks);
+}
+EXPORT_SYMBOL(clk_bulk_get_all);
+
+#ifdef CONFIG_HAVE_CLK_PREPARE
+
+/**
+ * clk_bulk_unprepare - undo preparation of a set of clock sources
+ * @num_clks: the number of clk_bulk_data
+ * @clks: the clk_bulk_data table being unprepared
+ *
+ * clk_bulk_unprepare may sleep, which differentiates it from clk_bulk_disable.
+ * Returns 0 on success, -EERROR otherwise.
+ */
+void clk_bulk_unprepare(int num_clks, const struct clk_bulk_data *clks)
+{
+	while (--num_clks >= 0)
+		clk_unprepare(clks[num_clks].clk);
+}
+EXPORT_SYMBOL_GPL(clk_bulk_unprepare);
+
+/**
+ * clk_bulk_prepare - prepare a set of clocks
+ * @num_clks: the number of clk_bulk_data
+ * @clks: the clk_bulk_data table being prepared
+ *
+ * clk_bulk_prepare may sleep, which differentiates it from clk_bulk_enable.
+ * Returns 0 on success, -EERROR otherwise.
+ */
+int __must_check clk_bulk_prepare(int num_clks,
+				  const struct clk_bulk_data *clks)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_clks; i++) {
+		ret = clk_prepare(clks[i].clk);
+		if (ret) {
+			pr_err("Failed to prepare clk '%s': %d\n",
+				clks[i].id, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	clk_bulk_unprepare(i, clks);
+
+	return  ret;
+}
+EXPORT_SYMBOL_GPL(clk_bulk_prepare);
+
+#endif /* CONFIG_HAVE_CLK_PREPARE */
+
+/**
+ * clk_bulk_disable - gate a set of clocks
+ * @num_clks: the number of clk_bulk_data
+ * @clks: the clk_bulk_data table being gated
+ *
+ * clk_bulk_disable must not sleep, which differentiates it from
+ * clk_bulk_unprepare. clk_bulk_disable must be called before
+ * clk_bulk_unprepare.
+ */
+void clk_bulk_disable(int num_clks, const struct clk_bulk_data *clks)
+{
+
+	while (--num_clks >= 0)
+		clk_disable(clks[num_clks].clk);
+}
+EXPORT_SYMBOL_GPL(clk_bulk_disable);
+
+/**
+ * clk_bulk_enable - ungate a set of clocks
+ * @num_clks: the number of clk_bulk_data
+ * @clks: the clk_bulk_data table being ungated
+ *
+ * clk_bulk_enable must not sleep
+ * Returns 0 on success, -EERROR otherwise.
+ */
+int __must_check clk_bulk_enable(int num_clks, const struct clk_bulk_data *clks)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_clks; i++) {
+		ret = clk_enable(clks[i].clk);
+		if (ret) {
+			pr_err("Failed to enable clk '%s': %d\n",
+				clks[i].id, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	clk_bulk_disable(i, clks);
+
+	return  ret;
+}
+EXPORT_SYMBOL_GPL(clk_bulk_enable);