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, 99 insertions, 0 deletions

diff --git a/sound/isa/adlib.c b/sound/isa/adlib.c
new file mode 100644
index 000000000..03fb2bce9
--- /dev/null
+++ b/sound/isa/adlib.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AdLib FM card driver.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/isa.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/opl3.h>
+
+#define CRD_NAME "AdLib FM"
+#define DEV_NAME "adlib"
+
+MODULE_DESCRIPTION(CRD_NAME);
+MODULE_AUTHOR("Rene Herman");
+MODULE_LICENSE("GPL");
+
+static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
+static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
+static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE;
+static long port[SNDRV_CARDS] = SNDRV_DEFAULT_PORT;
+
+module_param_array(index, int, NULL, 0444);
+MODULE_PARM_DESC(index, "Index value for " CRD_NAME " soundcard.");
+module_param_array(id, charp, NULL, 0444);
+MODULE_PARM_DESC(id, "ID string for " CRD_NAME " soundcard.");
+module_param_array(enable, bool, NULL, 0444);
+MODULE_PARM_DESC(enable, "Enable " CRD_NAME " soundcard.");
+module_param_hw_array(port, long, ioport, NULL, 0444);
+MODULE_PARM_DESC(port, "Port # for " CRD_NAME " driver.");
+
+static int snd_adlib_match(struct device *dev, unsigned int n)
+{
+	if (!enable[n])
+		return 0;
+
+	if (port[n] == SNDRV_AUTO_PORT) {
+		dev_err(dev, "please specify port\n");
+		return 0;
+	}
+	return 1;
+}
+
+static int snd_adlib_probe(struct device *dev, unsigned int n)
+{
+	struct snd_card *card;
+	struct snd_opl3 *opl3;
+	int error;
+
+	error = snd_devm_card_new(dev, index[n], id[n], THIS_MODULE, 0, &card);
+	if (error < 0) {
+		dev_err(dev, "could not create card\n");
+		return error;
+	}
+
+	card->private_data = devm_request_region(dev, port[n], 4, CRD_NAME);
+	if (!card->private_data) {
+		dev_err(dev, "could not grab ports\n");
+		return -EBUSY;
+	}
+
+	strscpy(card->driver, DEV_NAME);
+	strscpy(card->shortname, CRD_NAME);
+	sprintf(card->longname, CRD_NAME " at %#lx", port[n]);
+
+	error = snd_opl3_create(card, port[n], port[n] + 2, OPL3_HW_AUTO, 1, &opl3);
+	if (error < 0) {
+		dev_err(dev, "could not create OPL\n");
+		return error;
+	}
+
+	error = snd_opl3_hwdep_new(opl3, 0, 0, NULL);
+	if (error < 0) {
+		dev_err(dev, "could not create FM\n");
+		return error;
+	}
+
+	error = snd_card_register(card);
+	if (error < 0) {
+		dev_err(dev, "could not register card\n");
+		return error;
+	}
+
+	dev_set_drvdata(dev, card);
+	return 0;
+}
+
+static struct isa_driver snd_adlib_driver = {
+	.match		= snd_adlib_match,
+	.probe		= snd_adlib_probe,
+
+	.driver		= {
+		.name	= DEV_NAME
+	}
+};
+
+module_isa_driver(snd_adlib_driver, SNDRV_CARDS);