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, 165 insertions, 0 deletions

diff --git a/arch/arm/mach-omap1/timer.c b/arch/arm/mach-omap1/timer.c
new file mode 100644
index 000000000..399e6d840
--- /dev/null
+++ b/arch/arm/mach-omap1/timer.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * OMAP1 Dual-Mode Timers - platform device registration
+ *
+ * Contains first level initialization routines which internally
+ * generates timer device information and registers with linux
+ * device model. It also has a low level function to change the timer
+ * input clock source.
+ *
+ * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
+ * Tarun Kanti DebBarma <tarun.kanti@ti.com>
+ * Thara Gopinath <thara@ti.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/dmtimer-omap.h>
+#include <linux/soc/ti/omap1-io.h>
+
+#include <clocksource/timer-ti-dm.h>
+
+#include "soc.h"
+
+#define OMAP1610_GPTIMER1_BASE		0xfffb1400
+#define OMAP1610_GPTIMER2_BASE		0xfffb1c00
+#define OMAP1610_GPTIMER3_BASE		0xfffb2400
+#define OMAP1610_GPTIMER4_BASE		0xfffb2c00
+#define OMAP1610_GPTIMER5_BASE		0xfffb3400
+#define OMAP1610_GPTIMER6_BASE		0xfffb3c00
+#define OMAP1610_GPTIMER7_BASE		0xfffb7400
+#define OMAP1610_GPTIMER8_BASE		0xfffbd400
+
+#define OMAP1_DM_TIMER_COUNT		8
+
+static int omap1_dm_timer_set_src(struct platform_device *pdev,
+				int source)
+{
+	int n = (pdev->id - 1) << 1;
+	u32 l;
+
+	l = omap_readl(MOD_CONF_CTRL_1) & ~(0x03 << n);
+	l |= source << n;
+	omap_writel(l, MOD_CONF_CTRL_1);
+
+	return 0;
+}
+
+static int __init omap1_dm_timer_init(void)
+{
+	int i;
+	int ret;
+	struct dmtimer_platform_data *pdata;
+	struct platform_device *pdev;
+
+	if (!cpu_is_omap16xx())
+		return 0;
+
+	for (i = 1; i <= OMAP1_DM_TIMER_COUNT; i++) {
+		struct resource res[2];
+		u32 base, irq;
+
+		switch (i) {
+		case 1:
+			base = OMAP1610_GPTIMER1_BASE;
+			irq = INT_1610_GPTIMER1;
+			break;
+		case 2:
+			base = OMAP1610_GPTIMER2_BASE;
+			irq = INT_1610_GPTIMER2;
+			break;
+		case 3:
+			base = OMAP1610_GPTIMER3_BASE;
+			irq = INT_1610_GPTIMER3;
+			break;
+		case 4:
+			base = OMAP1610_GPTIMER4_BASE;
+			irq = INT_1610_GPTIMER4;
+			break;
+		case 5:
+			base = OMAP1610_GPTIMER5_BASE;
+			irq = INT_1610_GPTIMER5;
+			break;
+		case 6:
+			base = OMAP1610_GPTIMER6_BASE;
+			irq = INT_1610_GPTIMER6;
+			break;
+		case 7:
+			base = OMAP1610_GPTIMER7_BASE;
+			irq = INT_1610_GPTIMER7;
+			break;
+		case 8:
+			base = OMAP1610_GPTIMER8_BASE;
+			irq = INT_1610_GPTIMER8;
+			break;
+		default:
+			/*
+			 * not supposed to reach here.
+			 * this is to remove warning.
+			 */
+			return -EINVAL;
+		}
+
+		pdev = platform_device_alloc("omap_timer", i);
+		if (!pdev) {
+			pr_err("%s: Failed to device alloc for dmtimer%d\n",
+				__func__, i);
+			return -ENOMEM;
+		}
+
+		memset(res, 0, 2 * sizeof(struct resource));
+		res[0].start = base;
+		res[0].end = base + 0x46;
+		res[0].flags = IORESOURCE_MEM;
+		res[1].start = irq;
+		res[1].end = irq;
+		res[1].flags = IORESOURCE_IRQ;
+		ret = platform_device_add_resources(pdev, res,
+				ARRAY_SIZE(res));
+		if (ret) {
+			dev_err(&pdev->dev, "%s: Failed to add resources.\n",
+				__func__);
+			goto err_free_pdev;
+		}
+
+		pdata = kzalloc_obj(*pdata);
+		if (!pdata) {
+			ret = -ENOMEM;
+			goto err_free_pdata;
+		}
+
+		pdata->set_timer_src = omap1_dm_timer_set_src;
+		pdata->timer_capability = OMAP_TIMER_ALWON |
+				OMAP_TIMER_NEEDS_RESET | OMAP_TIMER_HAS_DSP_IRQ;
+
+		ret = platform_device_add_data(pdev, pdata, sizeof(*pdata));
+		if (ret) {
+			dev_err(&pdev->dev, "%s: Failed to add platform data.\n",
+				__func__);
+			goto err_free_pdata;
+		}
+
+		ret = platform_device_add(pdev);
+		if (ret) {
+			dev_err(&pdev->dev, "%s: Failed to add platform device.\n",
+				__func__);
+			goto err_free_pdata;
+		}
+
+		dev_dbg(&pdev->dev, " Registered.\n");
+	}
+
+	return 0;
+
+err_free_pdata:
+	kfree(pdata);
+
+err_free_pdev:
+	platform_device_put(pdev);
+
+	return ret;
+}
+arch_initcall(omap1_dm_timer_init);