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, 131 insertions, 0 deletions

diff --git a/sound/soc/sof/stream-ipc.c b/sound/soc/sof/stream-ipc.c
new file mode 100644
index 000000000..78758cf58
--- /dev/null
+++ b/sound/soc/sof/stream-ipc.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2019 Intel Corporation
+//
+// Authors: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
+
+/* Generic SOF IPC code */
+
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <sound/pcm.h>
+#include <sound/sof/stream.h>
+
+#include "ops.h"
+#include "sof-priv.h"
+#include "sof-audio.h"
+
+struct sof_stream {
+	size_t posn_offset;
+};
+
+/* Mailbox-based Generic IPC implementation */
+int sof_ipc_msg_data(struct snd_sof_dev *sdev,
+		     struct snd_sof_pcm_stream *sps,
+		     void *p, size_t sz)
+{
+	if (!sps || !sdev->stream_box.size) {
+		snd_sof_dsp_mailbox_read(sdev, sdev->dsp_box.offset, p, sz);
+	} else {
+		size_t posn_offset;
+
+		if (sps->substream) {
+			struct sof_stream *stream = sps->substream->runtime->private_data;
+
+			/* The stream might already be closed */
+			if (!stream)
+				return -ESTRPIPE;
+
+			posn_offset = stream->posn_offset;
+		} else if (sps->cstream) {
+
+			struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
+
+			if (!sstream)
+				return -ESTRPIPE;
+
+			posn_offset = sstream->posn_offset;
+
+		} else {
+			dev_err(sdev->dev, "%s: No stream opened\n", __func__);
+			return -EINVAL;
+		}
+
+		snd_sof_dsp_mailbox_read(sdev, posn_offset, p, sz);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_ipc_msg_data);
+
+int sof_set_stream_data_offset(struct snd_sof_dev *sdev,
+			       struct snd_sof_pcm_stream *sps,
+			       size_t posn_offset)
+{
+	/* check if offset is overflow or it is not aligned */
+	if (posn_offset > sdev->stream_box.size ||
+	    posn_offset % sizeof(struct sof_ipc_stream_posn) != 0)
+		return -EINVAL;
+
+	posn_offset += sdev->stream_box.offset;
+
+	if (sps->substream) {
+		struct sof_stream *stream = sps->substream->runtime->private_data;
+
+		stream->posn_offset = posn_offset;
+		dev_dbg(sdev->dev, "pcm: stream dir %d, posn mailbox offset is %zu",
+			sps->substream->stream, posn_offset);
+	} else if (sps->cstream) {
+		struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
+
+		sstream->posn_offset = posn_offset;
+		dev_dbg(sdev->dev, "compr: stream dir %d, posn mailbox offset is %zu",
+			sps->cstream->direction, posn_offset);
+	} else {
+		dev_err(sdev->dev, "No stream opened");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_set_stream_data_offset);
+
+int sof_stream_pcm_open(struct snd_sof_dev *sdev,
+			struct snd_pcm_substream *substream)
+{
+	struct sof_stream *stream = kmalloc_obj(*stream);
+
+	if (!stream)
+		return -ENOMEM;
+
+	/* binding pcm substream to hda stream */
+	substream->runtime->private_data = stream;
+
+	/* align to DMA minimum transfer size */
+	snd_pcm_hw_constraint_step(substream->runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 4);
+
+	/* avoid circular buffer wrap in middle of period */
+	snd_pcm_hw_constraint_integer(substream->runtime,
+				      SNDRV_PCM_HW_PARAM_PERIODS);
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_stream_pcm_open);
+
+int sof_stream_pcm_close(struct snd_sof_dev *sdev,
+			 struct snd_pcm_substream *substream)
+{
+	struct sof_stream *stream = substream->runtime->private_data;
+
+	substream->runtime->private_data = NULL;
+	kfree(stream);
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_stream_pcm_close);