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>

3 files changed, 101 insertions, 0 deletions

diff --git a/drivers/pmdomain/st/Kconfig b/drivers/pmdomain/st/Kconfig
new file mode 100644
index 000000000..a77a70211
--- /dev/null
+++ b/drivers/pmdomain/st/Kconfig
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config UX500_PM_DOMAIN
+	bool "ST-Ericsson ux500 Power Domain"
+	depends on ARCH_U8500 || COMPILE_TEST
+	default ARCH_U8500
diff --git a/drivers/pmdomain/st/Makefile b/drivers/pmdomain/st/Makefile
new file mode 100644
index 000000000..6d8b617eb
--- /dev/null
+++ b/drivers/pmdomain/st/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_UX500_PM_DOMAIN)		+= ste-ux500-pm-domain.o
diff --git a/drivers/pmdomain/st/ste-ux500-pm-domain.c b/drivers/pmdomain/st/ste-ux500-pm-domain.c
new file mode 100644
index 000000000..6896cb4a7
--- /dev/null
+++ b/drivers/pmdomain/st/ste-ux500-pm-domain.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * Implements PM domains using the generic PM domain for ux500.
+ */
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pm_domain.h>
+
+#include <dt-bindings/arm/ux500_pm_domains.h>
+
+static int pd_power_off(struct generic_pm_domain *domain)
+{
+	/*
+	 * Handle the gating of the PM domain regulator here.
+	 *
+	 * Drivers/subsystems handling devices in the PM domain needs to perform
+	 * register context save/restore from their respective runtime PM
+	 * callbacks, to be able to enable PM domain gating/ungating.
+	 */
+	return 0;
+}
+
+static int pd_power_on(struct generic_pm_domain *domain)
+{
+	/*
+	 * Handle the ungating of the PM domain regulator here.
+	 *
+	 * Drivers/subsystems handling devices in the PM domain needs to perform
+	 * register context save/restore from their respective runtime PM
+	 * callbacks, to be able to enable PM domain gating/ungating.
+	 */
+	return 0;
+}
+
+static struct generic_pm_domain ux500_pm_domain_vape = {
+	.name = "VAPE",
+	.power_off = pd_power_off,
+	.power_on = pd_power_on,
+};
+
+static struct generic_pm_domain *ux500_pm_domains[NR_DOMAINS] = {
+	[DOMAIN_VAPE] = &ux500_pm_domain_vape,
+};
+
+static const struct of_device_id ux500_pm_domain_matches[] = {
+	{ .compatible = "stericsson,ux500-pm-domains", },
+	{ },
+};
+
+static int ux500_pm_domains_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct genpd_onecell_data *genpd_data;
+	int i;
+
+	if (!np)
+		return -ENODEV;
+
+	genpd_data = kzalloc_obj(*genpd_data);
+	if (!genpd_data)
+		return -ENOMEM;
+
+	genpd_data->domains = ux500_pm_domains;
+	genpd_data->num_domains = ARRAY_SIZE(ux500_pm_domains);
+
+	for (i = 0; i < ARRAY_SIZE(ux500_pm_domains); ++i)
+		pm_genpd_init(ux500_pm_domains[i], NULL, false);
+
+	of_genpd_add_provider_onecell(np, genpd_data);
+	return 0;
+}
+
+static struct platform_driver ux500_pm_domains_driver = {
+	.probe  = ux500_pm_domains_probe,
+	.driver = {
+		.name = "ux500_pm_domains",
+		.of_match_table = ux500_pm_domain_matches,
+	},
+};
+
+static int __init ux500_pm_domains_init(void)
+{
+	return platform_driver_register(&ux500_pm_domains_driver);
+}
+arch_initcall(ux500_pm_domains_init);