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, 82 insertions, 0 deletions

diff --git a/include/sound/ac97/controller.h b/include/sound/ac97/controller.h
new file mode 100644
index 000000000..d5895ea39
--- /dev/null
+++ b/include/sound/ac97/controller.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2016 Robert Jarzmik <robert.jarzmik@free.fr>
+ */
+
+#ifndef AC97_CONTROLLER_H
+#define AC97_CONTROLLER_H
+
+#include <linux/device.h>
+#include <linux/list.h>
+
+#define AC97_BUS_MAX_CODECS 4
+#define AC97_SLOTS_AVAILABLE_ALL 0xf
+
+struct ac97_controller_ops;
+
+/**
+ * struct ac97_controller - The AC97 controller of the AC-Link
+ * @ops:		the AC97 operations.
+ * @controllers:	linked list of all existing controllers.
+ * @adap:		the shell device ac97-%d, ie. ac97 adapter
+ * @nr:			the number of the shell device
+ * @slots_available:	the mask of accessible/scanable codecs.
+ * @parent:		the device providing the AC97 controller.
+ * @codecs:		the 4 possible AC97 codecs (NULL if none found).
+ * @codecs_pdata:	platform_data for each codec (NULL if no pdata).
+ *
+ * This structure is internal to AC97 bus, and should not be used by the
+ * controllers themselves, excepting for using @dev.
+ */
+struct ac97_controller {
+	const struct ac97_controller_ops *ops;
+	struct list_head controllers;
+	struct device adap;
+	int nr;
+	unsigned short slots_available;
+	struct device *parent;
+	struct ac97_codec_device *codecs[AC97_BUS_MAX_CODECS];
+	void *codecs_pdata[AC97_BUS_MAX_CODECS];
+};
+
+/**
+ * struct ac97_controller_ops - The AC97 operations
+ * @reset:	Cold reset of the AC97 AC-Link.
+ * @warm_reset:	Warm reset of the AC97 AC-Link.
+ * @read:	Read of a single AC97 register.
+ *		Returns the register value or a negative error code.
+ * @write:	Write of a single AC97 register.
+ *
+ * These are the basic operation an AC97 controller must provide for an AC97
+ * access functions. Amongst these, all but the last 2 are mandatory.
+ * The slot number is also known as the AC97 codec number, between 0 and 3.
+ */
+struct ac97_controller_ops {
+	void (*reset)(struct ac97_controller *adrv);
+	void (*warm_reset)(struct ac97_controller *adrv);
+	int (*write)(struct ac97_controller *adrv, int slot,
+		     unsigned short reg, unsigned short val);
+	int (*read)(struct ac97_controller *adrv, int slot, unsigned short reg);
+};
+
+#if IS_ENABLED(CONFIG_AC97_BUS_NEW)
+struct ac97_controller *snd_ac97_controller_register(
+	const struct ac97_controller_ops *ops, struct device *dev,
+	unsigned short slots_available);
+void snd_ac97_controller_unregister(struct ac97_controller *ac97_ctrl);
+#else
+static inline struct ac97_controller *
+snd_ac97_controller_register(const struct ac97_controller_ops *ops,
+			     struct device *dev,
+			     unsigned short slots_available)
+{
+	return ERR_PTR(-ENODEV);
+}
+
+static inline void
+snd_ac97_controller_unregister(struct ac97_controller *ac97_ctrl)
+{
+}
+#endif
+
+#endif