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, 209 insertions, 0 deletions

diff --git a/drivers/scsi/jazz_esp.c b/drivers/scsi/jazz_esp.c
new file mode 100644
index 000000000..35137f5cf
--- /dev/null
+++ b/drivers/scsi/jazz_esp.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* jazz_esp.c: ESP front-end for MIPS JAZZ systems.
+ *
+ * Copyright (C) 2007 Thomas Bogendörfer (tsbogend@alpha.frankende)
+ */
+
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+
+#include <asm/irq.h>
+#include <asm/io.h>
+#include <asm/dma.h>
+
+#include <asm/jazz.h>
+#include <asm/jazzdma.h>
+
+#include <scsi/scsi_host.h>
+
+#include "esp_scsi.h"
+
+#define DRV_MODULE_NAME		"jazz_esp"
+#define PFX DRV_MODULE_NAME	": "
+#define DRV_VERSION		"1.000"
+#define DRV_MODULE_RELDATE	"May 19, 2007"
+
+static void jazz_esp_write8(struct esp *esp, u8 val, unsigned long reg)
+{
+	*(volatile u8 *)(esp->regs + reg) = val;
+}
+
+static u8 jazz_esp_read8(struct esp *esp, unsigned long reg)
+{
+	return *(volatile u8 *)(esp->regs + reg);
+}
+
+static int jazz_esp_irq_pending(struct esp *esp)
+{
+	if (jazz_esp_read8(esp, ESP_STATUS) & ESP_STAT_INTR)
+		return 1;
+	return 0;
+}
+
+static void jazz_esp_reset_dma(struct esp *esp)
+{
+	vdma_disable ((int)esp->dma_regs);
+}
+
+static void jazz_esp_dma_drain(struct esp *esp)
+{
+	/* nothing to do */
+}
+
+static void jazz_esp_dma_invalidate(struct esp *esp)
+{
+	vdma_disable ((int)esp->dma_regs);
+}
+
+static void jazz_esp_send_dma_cmd(struct esp *esp, u32 addr, u32 esp_count,
+				  u32 dma_count, int write, u8 cmd)
+{
+	BUG_ON(!(cmd & ESP_CMD_DMA));
+
+	jazz_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
+	jazz_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
+	vdma_disable ((int)esp->dma_regs);
+	if (write)
+		vdma_set_mode ((int)esp->dma_regs, DMA_MODE_READ);
+	else
+		vdma_set_mode ((int)esp->dma_regs, DMA_MODE_WRITE);
+
+	vdma_set_addr ((int)esp->dma_regs, addr);
+	vdma_set_count ((int)esp->dma_regs, dma_count);
+	vdma_enable ((int)esp->dma_regs);
+
+	scsi_esp_cmd(esp, cmd);
+}
+
+static int jazz_esp_dma_error(struct esp *esp)
+{
+	u32 enable = vdma_get_enable((int)esp->dma_regs);
+
+	if (enable & (R4030_MEM_INTR|R4030_ADDR_INTR))
+		return 1;
+
+	return 0;
+}
+
+static const struct esp_driver_ops jazz_esp_ops = {
+	.esp_write8	=	jazz_esp_write8,
+	.esp_read8	=	jazz_esp_read8,
+	.irq_pending	=	jazz_esp_irq_pending,
+	.reset_dma	=	jazz_esp_reset_dma,
+	.dma_drain	=	jazz_esp_dma_drain,
+	.dma_invalidate	=	jazz_esp_dma_invalidate,
+	.send_dma_cmd	=	jazz_esp_send_dma_cmd,
+	.dma_error	=	jazz_esp_dma_error,
+};
+
+static int esp_jazz_probe(struct platform_device *dev)
+{
+	const struct scsi_host_template *tpnt = &scsi_esp_template;
+	struct Scsi_Host *host;
+	struct esp *esp;
+	struct resource *res;
+	int err;
+
+	host = scsi_host_alloc(tpnt, sizeof(struct esp));
+
+	err = -ENOMEM;
+	if (!host)
+		goto fail;
+
+	host->max_id = 8;
+	esp = shost_priv(host);
+
+	esp->host = host;
+	esp->dev = &dev->dev;
+	esp->ops = &jazz_esp_ops;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto fail_unlink;
+
+	esp->regs = (void __iomem *)res->start;
+	if (!esp->regs)
+		goto fail_unlink;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 1);
+	if (!res)
+		goto fail_unlink;
+
+	esp->dma_regs = (void __iomem *)res->start;
+
+	esp->command_block = dma_alloc_coherent(esp->dev, 16,
+						&esp->command_block_dma,
+						GFP_KERNEL);
+	if (!esp->command_block)
+		goto fail_unmap_regs;
+
+	host->irq = err = platform_get_irq(dev, 0);
+	if (err < 0)
+		goto fail_unmap_command_block;
+	err = request_irq(host->irq, scsi_esp_intr, IRQF_SHARED, "ESP", esp);
+	if (err < 0)
+		goto fail_unmap_command_block;
+
+	esp->scsi_id = 7;
+	esp->host->this_id = esp->scsi_id;
+	esp->scsi_id_mask = (1 << esp->scsi_id);
+	esp->cfreq = 40000000;
+
+	dev_set_drvdata(&dev->dev, esp);
+
+	err = scsi_esp_register(esp);
+	if (err)
+		goto fail_free_irq;
+
+	return 0;
+
+fail_free_irq:
+	free_irq(host->irq, esp);
+fail_unmap_command_block:
+	dma_free_coherent(esp->dev, 16,
+			  esp->command_block,
+			  esp->command_block_dma);
+fail_unmap_regs:
+fail_unlink:
+	scsi_host_put(host);
+fail:
+	return err;
+}
+
+static void esp_jazz_remove(struct platform_device *dev)
+{
+	struct esp *esp = dev_get_drvdata(&dev->dev);
+	unsigned int irq = esp->host->irq;
+
+	scsi_esp_unregister(esp);
+
+	free_irq(irq, esp);
+	dma_free_coherent(esp->dev, 16,
+			  esp->command_block,
+			  esp->command_block_dma);
+
+	scsi_host_put(esp->host);
+}
+
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:jazz_esp");
+
+static struct platform_driver esp_jazz_driver = {
+	.probe		= esp_jazz_probe,
+	.remove		= esp_jazz_remove,
+	.driver	= {
+		.name	= "jazz_esp",
+	},
+};
+module_platform_driver(esp_jazz_driver);
+
+MODULE_DESCRIPTION("JAZZ ESP SCSI driver");
+MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);