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, 65 insertions, 0 deletions

diff --git a/arch/mips/bcm63xx/dev-usb-usbd.c b/arch/mips/bcm63xx/dev-usb-usbd.c
new file mode 100644
index 000000000..508bd9d8d
--- /dev/null
+++ b/arch/mips/bcm63xx/dev-usb-usbd.c
@@ -0,0 +1,65 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2008 Maxime Bizon <mbizon@freebox.fr>
+ * Copyright (C) 2012 Kevin Cernekee <cernekee@gmail.com>
+ * Copyright (C) 2012 Broadcom Corporation
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <bcm63xx_cpu.h>
+#include <bcm63xx_dev_usb_usbd.h>
+
+#define NUM_MMIO		2
+#define NUM_IRQ			7
+
+static struct resource usbd_resources[NUM_MMIO + NUM_IRQ];
+
+static u64 usbd_dmamask = DMA_BIT_MASK(32);
+
+static struct platform_device bcm63xx_usbd_device = {
+	.name		= "bcm63xx_udc",
+	.id		= -1,
+	.num_resources	= ARRAY_SIZE(usbd_resources),
+	.resource	= usbd_resources,
+	.dev		= {
+		.dma_mask		= &usbd_dmamask,
+		.coherent_dma_mask	= DMA_BIT_MASK(32),
+	},
+};
+
+int __init bcm63xx_usbd_register(const struct bcm63xx_usbd_platform_data *pd)
+{
+	const int irq_list[NUM_IRQ] = { IRQ_USBD,
+		IRQ_USBD_RXDMA0, IRQ_USBD_TXDMA0,
+		IRQ_USBD_RXDMA1, IRQ_USBD_TXDMA1,
+		IRQ_USBD_RXDMA2, IRQ_USBD_TXDMA2 };
+	int i;
+
+	if (!BCMCPU_IS_6328() && !BCMCPU_IS_6368())
+		return 0;
+
+	usbd_resources[0].start = bcm63xx_regset_address(RSET_USBD);
+	usbd_resources[0].end = usbd_resources[0].start + RSET_USBD_SIZE - 1;
+	usbd_resources[0].flags = IORESOURCE_MEM;
+
+	usbd_resources[1].start = bcm63xx_regset_address(RSET_USBDMA);
+	usbd_resources[1].end = usbd_resources[1].start + RSET_USBDMA_SIZE - 1;
+	usbd_resources[1].flags = IORESOURCE_MEM;
+
+	for (i = 0; i < NUM_IRQ; i++) {
+		struct resource *r = &usbd_resources[NUM_MMIO + i];
+
+		r->start = r->end = bcm63xx_get_irq_number(irq_list[i]);
+		r->flags = IORESOURCE_IRQ;
+	}
+
+	platform_device_add_data(&bcm63xx_usbd_device, pd, sizeof(*pd));
+
+	return platform_device_register(&bcm63xx_usbd_device);
+}