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, 190 insertions, 0 deletions

diff --git a/sound/ppc/powermac.c b/sound/ppc/powermac.c
new file mode 100644
index 000000000..e685d2458
--- /dev/null
+++ b/sound/ppc/powermac.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for PowerMac AWACS
+ * Copyright (c) 2001 by Takashi Iwai <tiwai@suse.de>
+ *   based on dmasound.c.
+ */
+
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include "pmac.h"
+#include "awacs.h"
+#include "burgundy.h"
+
+#define CHIP_NAME "PMac"
+
+MODULE_DESCRIPTION("PowerMac");
+MODULE_LICENSE("GPL");
+
+static int index = SNDRV_DEFAULT_IDX1;		/* Index 0-MAX */
+static char *id = SNDRV_DEFAULT_STR1;		/* ID for this card */
+static bool enable_beep = 1;
+
+module_param(index, int, 0444);
+MODULE_PARM_DESC(index, "Index value for " CHIP_NAME " soundchip.");
+module_param(id, charp, 0444);
+MODULE_PARM_DESC(id, "ID string for " CHIP_NAME " soundchip.");
+module_param(enable_beep, bool, 0444);
+MODULE_PARM_DESC(enable_beep, "Enable beep using PCM.");
+
+static struct platform_device *device;
+
+
+/*
+ */
+
+static int snd_pmac_probe(struct platform_device *devptr)
+{
+	struct snd_card *card;
+	struct snd_pmac *chip;
+	char *name_ext;
+	int err;
+
+	err = snd_card_new(&devptr->dev, index, id, THIS_MODULE, 0, &card);
+	if (err < 0)
+		return err;
+
+	err = snd_pmac_new(card, &chip);
+	if (err < 0)
+		goto __error;
+	card->private_data = chip;
+
+	switch (chip->model) {
+	case PMAC_BURGUNDY:
+		strscpy(card->driver, "PMac Burgundy");
+		strscpy(card->shortname, "PowerMac Burgundy");
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_burgundy_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_DACA:
+		strscpy(card->driver, "PMac DACA");
+		strscpy(card->shortname, "PowerMac DACA");
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_daca_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_TUMBLER:
+	case PMAC_SNAPPER:
+		name_ext = chip->model == PMAC_TUMBLER ? "Tumbler" : "Snapper";
+		sprintf(card->driver, "PMac %s", name_ext);
+		sprintf(card->shortname, "PowerMac %s", name_ext);
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_tumbler_init(chip);
+		if (err < 0)
+			goto __error;
+		err = snd_pmac_tumbler_post_init();
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_AWACS:
+	case PMAC_SCREAMER:
+		name_ext = chip->model == PMAC_SCREAMER ? "Screamer" : "AWACS";
+		sprintf(card->driver, "PMac %s", name_ext);
+		sprintf(card->shortname, "PowerMac %s", name_ext);
+		if (chip->is_pbook_3400)
+			name_ext = " [PB3400]";
+		else if (chip->is_pbook_G3)
+			name_ext = " [PBG3]";
+		else
+			name_ext = "";
+		sprintf(card->longname, "%s%s Rev %d",
+			card->shortname, name_ext, chip->revision);
+		err = snd_pmac_awacs_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	default:
+		dev_err(&devptr->dev, "unsupported hardware %d\n", chip->model);
+		err = -EINVAL;
+		goto __error;
+	}
+
+	err = snd_pmac_pcm_new(chip);
+	if (err < 0)
+		goto __error;
+
+	chip->initialized = 1;
+	if (enable_beep)
+		snd_pmac_attach_beep(chip);
+
+	err = snd_card_register(card);
+	if (err < 0)
+		goto __error;
+
+	platform_set_drvdata(devptr, card);
+	return 0;
+
+__error:
+	snd_card_free(card);
+	return err;
+}
+
+
+static void snd_pmac_remove(struct platform_device *devptr)
+{
+	snd_card_free(platform_get_drvdata(devptr));
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int snd_pmac_driver_suspend(struct device *dev)
+{
+	struct snd_card *card = dev_get_drvdata(dev);
+	snd_pmac_suspend(card->private_data);
+	return 0;
+}
+
+static int snd_pmac_driver_resume(struct device *dev)
+{
+	struct snd_card *card = dev_get_drvdata(dev);
+	snd_pmac_resume(card->private_data);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(snd_pmac_pm, snd_pmac_driver_suspend, snd_pmac_driver_resume);
+#define SND_PMAC_PM_OPS	&snd_pmac_pm
+#else
+#define SND_PMAC_PM_OPS	NULL
+#endif
+
+#define SND_PMAC_DRIVER		"snd_powermac"
+
+static struct platform_driver snd_pmac_driver = {
+	.probe		= snd_pmac_probe,
+	.remove		= snd_pmac_remove,
+	.driver		= {
+		.name	= SND_PMAC_DRIVER,
+		.pm	= SND_PMAC_PM_OPS,
+	},
+};
+
+static int __init alsa_card_pmac_init(void)
+{
+	int err;
+
+	err = platform_driver_register(&snd_pmac_driver);
+	if (err < 0)
+		return err;
+	device = platform_device_register_simple(SND_PMAC_DRIVER, -1, NULL, 0);
+	return 0;
+
+}
+
+static void __exit alsa_card_pmac_exit(void)
+{
+	if (!IS_ERR(device))
+		platform_device_unregister(device);
+	platform_driver_unregister(&snd_pmac_driver);
+}
+
+module_init(alsa_card_pmac_init)
+module_exit(alsa_card_pmac_exit)