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, 101 insertions, 0 deletions

diff --git a/drivers/video/fbdev/sa1100fb.h b/drivers/video/fbdev/sa1100fb.h
new file mode 100644
index 000000000..b4363444f
--- /dev/null
+++ b/drivers/video/fbdev/sa1100fb.h
@@ -0,0 +1,101 @@
+/*
+ * linux/drivers/video/sa1100fb.h
+ *    -- StrongARM 1100 LCD Controller Frame Buffer Device
+ *
+ *  Copyright (C) 1999 Eric A. Thomas
+ *   Based on acornfb.c Copyright (C) Russell King.
+ *  
+ * 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.
+ */
+
+struct gpio_desc;
+
+#define LCCR0           0x0000          /* LCD Control Reg. 0 */
+#define LCSR            0x0004          /* LCD Status Reg. */
+#define DBAR1           0x0010          /* LCD DMA Base Address Reg. channel 1 */
+#define DCAR1           0x0014          /* LCD DMA Current Address Reg. channel 1 */
+#define DBAR2           0x0018          /* LCD DMA Base Address Reg.  channel 2 */
+#define DCAR2           0x001C          /* LCD DMA Current Address Reg. channel 2 */
+#define LCCR1           0x0020          /* LCD Control Reg. 1 */
+#define LCCR2           0x0024          /* LCD Control Reg. 2 */
+#define LCCR3           0x0028          /* LCD Control Reg. 3 */
+
+/* Shadows for LCD controller registers */
+struct sa1100fb_lcd_reg {
+	unsigned long lccr0;
+	unsigned long lccr1;
+	unsigned long lccr2;
+	unsigned long lccr3;
+};
+
+struct sa1100fb_info {
+	struct fb_info		fb;
+	struct device		*dev;
+	const struct sa1100fb_rgb *rgb[NR_RGB];
+	void __iomem		*base;
+	struct gpio_desc	*shannon_lcden;
+
+	/*
+	 * These are the addresses we mapped
+	 * the framebuffer memory region to.
+	 */
+	dma_addr_t		map_dma;
+	u_char *		map_cpu;
+	u_int			map_size;
+
+	u_char *		screen_cpu;
+	dma_addr_t		screen_dma;
+	u16 *			palette_cpu;
+	dma_addr_t		palette_dma;
+	u_int			palette_size;
+
+	dma_addr_t		dbar1;
+	dma_addr_t		dbar2;
+
+	u_int			reg_lccr0;
+	u_int			reg_lccr1;
+	u_int			reg_lccr2;
+	u_int			reg_lccr3;
+
+	volatile u_char		state;
+	volatile u_char		task_state;
+	struct mutex		ctrlr_lock;
+	wait_queue_head_t	ctrlr_wait;
+	struct work_struct	task;
+
+#ifdef CONFIG_CPU_FREQ
+	struct notifier_block	freq_transition;
+#endif
+
+	const struct sa1100fb_mach_info *inf;
+	struct clk *clk;
+
+	u32 pseudo_palette[16];
+};
+
+#define TO_INF(ptr,member)	container_of(ptr,struct sa1100fb_info,member)
+
+#define SA1100_PALETTE_MODE_VAL(bpp)    (((bpp) & 0x018) << 9)
+
+/*
+ * These are the actions for set_ctrlr_state
+ */
+#define C_DISABLE		(0)
+#define C_ENABLE		(1)
+#define C_DISABLE_CLKCHANGE	(2)
+#define C_ENABLE_CLKCHANGE	(3)
+#define C_REENABLE		(4)
+#define C_DISABLE_PM		(5)
+#define C_ENABLE_PM		(6)
+#define C_STARTUP		(7)
+
+#define SA1100_NAME	"SA1100"
+
+/*
+ * Minimum X and Y resolutions
+ */
+#define MIN_XRES	64
+#define MIN_YRES	64
+