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, 344 insertions, 0 deletions

diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
new file mode 100644
index 000000000..994d5bc51
--- /dev/null
+++ b/drivers/clk/clk-devres.c
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+
+struct devm_clk_state {
+	struct clk *clk;
+	void (*exit)(struct clk *clk);
+};
+
+static void devm_clk_release(struct device *dev, void *res)
+{
+	struct devm_clk_state *state = res;
+
+	if (state->exit)
+		state->exit(state->clk);
+
+	clk_put(state->clk);
+}
+
+static struct clk *__devm_clk_get(struct device *dev, const char *id,
+				  struct clk *(*get)(struct device *dev, const char *id),
+				  int (*init)(struct clk *clk),
+				  void (*exit)(struct clk *clk))
+{
+	struct devm_clk_state *state;
+	struct clk *clk;
+	int ret;
+
+	state = devres_alloc(devm_clk_release, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return ERR_PTR(-ENOMEM);
+
+	clk = get(dev, id);
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		goto err_clk_get;
+	}
+
+	if (init) {
+		ret = init(clk);
+		if (ret)
+			goto err_clk_init;
+	}
+
+	state->clk = clk;
+	state->exit = exit;
+
+	devres_add(dev, state);
+
+	return clk;
+
+err_clk_init:
+
+	clk_put(clk);
+err_clk_get:
+
+	devres_free(state);
+	return ERR_PTR(ret);
+}
+
+struct clk *devm_clk_get(struct device *dev, const char *id)
+{
+	return __devm_clk_get(dev, id, clk_get, NULL, NULL);
+}
+EXPORT_SYMBOL(devm_clk_get);
+
+struct clk *devm_clk_get_prepared(struct device *dev, const char *id)
+{
+	return __devm_clk_get(dev, id, clk_get, clk_prepare, clk_unprepare);
+}
+EXPORT_SYMBOL_GPL(devm_clk_get_prepared);
+
+struct clk *devm_clk_get_enabled(struct device *dev, const char *id)
+{
+	return __devm_clk_get(dev, id, clk_get,
+			      clk_prepare_enable, clk_disable_unprepare);
+}
+EXPORT_SYMBOL_GPL(devm_clk_get_enabled);
+
+struct clk *devm_clk_get_optional(struct device *dev, const char *id)
+{
+	return __devm_clk_get(dev, id, clk_get_optional, NULL, NULL);
+}
+EXPORT_SYMBOL(devm_clk_get_optional);
+
+struct clk *devm_clk_get_optional_prepared(struct device *dev, const char *id)
+{
+	return __devm_clk_get(dev, id, clk_get_optional,
+			      clk_prepare, clk_unprepare);
+}
+EXPORT_SYMBOL_GPL(devm_clk_get_optional_prepared);
+
+struct clk *devm_clk_get_optional_enabled(struct device *dev, const char *id)
+{
+	return __devm_clk_get(dev, id, clk_get_optional,
+			      clk_prepare_enable, clk_disable_unprepare);
+}
+EXPORT_SYMBOL_GPL(devm_clk_get_optional_enabled);
+
+struct clk *devm_clk_get_optional_enabled_with_rate(struct device *dev,
+						    const char *id,
+						    unsigned long rate)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = __devm_clk_get(dev, id, clk_get_optional, NULL,
+			     clk_disable_unprepare);
+	if (IS_ERR(clk))
+		return ERR_CAST(clk);
+
+	ret = clk_set_rate(clk, rate);
+	if (ret)
+		goto out_put_clk;
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		goto out_put_clk;
+
+	return clk;
+
+out_put_clk:
+	devm_clk_put(dev, clk);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(devm_clk_get_optional_enabled_with_rate);
+
+struct clk_bulk_devres {
+	struct clk_bulk_data *clks;
+	int num_clks;
+};
+
+static void devm_clk_bulk_release(struct device *dev, void *res)
+{
+	struct clk_bulk_devres *devres = res;
+
+	clk_bulk_put(devres->num_clks, devres->clks);
+}
+
+static int __devm_clk_bulk_get(struct device *dev, int num_clks,
+			       struct clk_bulk_data *clks, bool optional)
+{
+	struct clk_bulk_devres *devres;
+	int ret;
+
+	devres = devres_alloc(devm_clk_bulk_release,
+			      sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	if (optional)
+		ret = clk_bulk_get_optional(dev, num_clks, clks);
+	else
+		ret = clk_bulk_get(dev, num_clks, clks);
+	if (!ret) {
+		devres->clks = clks;
+		devres->num_clks = num_clks;
+		devres_add(dev, devres);
+	} else {
+		devres_free(devres);
+	}
+
+	return ret;
+}
+
+int __must_check devm_clk_bulk_get(struct device *dev, int num_clks,
+		      struct clk_bulk_data *clks)
+{
+	return __devm_clk_bulk_get(dev, num_clks, clks, false);
+}
+EXPORT_SYMBOL_GPL(devm_clk_bulk_get);
+
+int __must_check devm_clk_bulk_get_optional(struct device *dev, int num_clks,
+		      struct clk_bulk_data *clks)
+{
+	return __devm_clk_bulk_get(dev, num_clks, clks, true);
+}
+EXPORT_SYMBOL_GPL(devm_clk_bulk_get_optional);
+
+static void devm_clk_bulk_release_enable(struct device *dev, void *res)
+{
+	struct clk_bulk_devres *devres = res;
+
+	clk_bulk_disable_unprepare(devres->num_clks, devres->clks);
+	clk_bulk_put(devres->num_clks, devres->clks);
+}
+
+static int __devm_clk_bulk_get_enable(struct device *dev, int num_clks,
+				      struct clk_bulk_data *clks, bool optional)
+{
+	struct clk_bulk_devres *devres;
+	int ret;
+
+	devres = devres_alloc(devm_clk_bulk_release_enable,
+			      sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	if (optional)
+		ret = clk_bulk_get_optional(dev, num_clks, clks);
+	else
+		ret = clk_bulk_get(dev, num_clks, clks);
+	if (ret)
+		goto err_clk_get;
+
+	ret = clk_bulk_prepare_enable(num_clks, clks);
+	if (ret)
+		goto err_clk_prepare;
+
+	devres->clks = clks;
+	devres->num_clks = num_clks;
+	devres_add(dev, devres);
+
+	return 0;
+
+err_clk_prepare:
+	clk_bulk_put(num_clks, clks);
+err_clk_get:
+	devres_free(devres);
+	return ret;
+}
+
+int __must_check devm_clk_bulk_get_optional_enable(struct device *dev, int num_clks,
+						   struct clk_bulk_data *clks)
+{
+	return __devm_clk_bulk_get_enable(dev, num_clks, clks, true);
+}
+EXPORT_SYMBOL_GPL(devm_clk_bulk_get_optional_enable);
+
+static void devm_clk_bulk_release_all(struct device *dev, void *res)
+{
+	struct clk_bulk_devres *devres = res;
+
+	clk_bulk_put_all(devres->num_clks, devres->clks);
+}
+
+int __must_check devm_clk_bulk_get_all(struct device *dev,
+				       struct clk_bulk_data **clks)
+{
+	struct clk_bulk_devres *devres;
+	int ret;
+
+	devres = devres_alloc(devm_clk_bulk_release_all,
+			      sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	ret = clk_bulk_get_all(dev, &devres->clks);
+	if (ret > 0) {
+		*clks = devres->clks;
+		devres->num_clks = ret;
+		devres_add(dev, devres);
+	} else {
+		devres_free(devres);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all);
+
+static void devm_clk_bulk_release_all_enable(struct device *dev, void *res)
+{
+	struct clk_bulk_devres *devres = res;
+
+	clk_bulk_disable_unprepare(devres->num_clks, devres->clks);
+	clk_bulk_put_all(devres->num_clks, devres->clks);
+}
+
+int __must_check devm_clk_bulk_get_all_enabled(struct device *dev,
+					       struct clk_bulk_data **clks)
+{
+	struct clk_bulk_devres *devres;
+	int ret;
+
+	devres = devres_alloc(devm_clk_bulk_release_all_enable,
+			      sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	ret = clk_bulk_get_all(dev, &devres->clks);
+	if (ret > 0) {
+		*clks = devres->clks;
+		devres->num_clks = ret;
+	} else {
+		devres_free(devres);
+		return ret;
+	}
+
+	ret = clk_bulk_prepare_enable(devres->num_clks, *clks);
+	if (!ret) {
+		devres_add(dev, devres);
+	} else {
+		clk_bulk_put_all(devres->num_clks, devres->clks);
+		devres_free(devres);
+		return ret;
+	}
+
+	return devres->num_clks;
+}
+EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all_enabled);
+
+static int devm_clk_match(struct device *dev, void *res, void *data)
+{
+	struct clk **c = res;
+	if (!c || !*c) {
+		WARN_ON(!c || !*c);
+		return 0;
+	}
+	return *c == data;
+}
+
+void devm_clk_put(struct device *dev, struct clk *clk)
+{
+	int ret;
+
+	ret = devres_release(dev, devm_clk_release, devm_clk_match, clk);
+
+	WARN_ON(ret);
+}
+EXPORT_SYMBOL(devm_clk_put);
+
+struct clk *devm_get_clk_from_child(struct device *dev,
+				    struct device_node *np, const char *con_id)
+{
+	struct devm_clk_state *state;
+	struct clk *clk;
+
+	state = devres_alloc(devm_clk_release, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return ERR_PTR(-ENOMEM);
+
+	clk = of_clk_get_by_name(np, con_id);
+	if (!IS_ERR(clk)) {
+		state->clk = clk;
+		devres_add(dev, state);
+	} else {
+		devres_free(state);
+	}
+
+	return clk;
+}
+EXPORT_SYMBOL(devm_get_clk_from_child);