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, 168 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-sysfs.c b/drivers/usb/host/ehci-sysfs.c
new file mode 100644
index 000000000..5e6b545c3
--- /dev/null
+++ b/drivers/usb/host/ehci-sysfs.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2007 by Alan Stern
+ */
+
+/* this file is part of ehci-hcd.c */
+
+
+/* Display the ports dedicated to the companion controller */
+static ssize_t companion_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct ehci_hcd		*ehci;
+	int			nports, index;
+	int			len = 0;
+
+	ehci = hcd_to_ehci(dev_get_drvdata(dev));
+	nports = HCS_N_PORTS(ehci->hcs_params);
+
+	for (index = 0; index < nports; ++index) {
+		if (test_bit(index, &ehci->companion_ports))
+			len += sysfs_emit_at(buf, len, "%d\n", index + 1);
+	}
+	return len;
+}
+
+/*
+ * Dedicate or undedicate a port to the companion controller.
+ * Syntax is "[-]portnum", where a leading '-' sign means
+ * return control of the port to the EHCI controller.
+ */
+static ssize_t companion_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct ehci_hcd		*ehci;
+	int			portnum, new_owner;
+
+	ehci = hcd_to_ehci(dev_get_drvdata(dev));
+	new_owner = PORT_OWNER;		/* Owned by companion */
+	if (sscanf(buf, "%d", &portnum) != 1)
+		return -EINVAL;
+	if (portnum < 0) {
+		portnum = - portnum;
+		new_owner = 0;		/* Owned by EHCI */
+	}
+	if (portnum <= 0 || portnum > HCS_N_PORTS(ehci->hcs_params))
+		return -ENOENT;
+	portnum--;
+	if (new_owner)
+		set_bit(portnum, &ehci->companion_ports);
+	else
+		clear_bit(portnum, &ehci->companion_ports);
+	set_owner(ehci, portnum, new_owner);
+	return count;
+}
+static DEVICE_ATTR_RW(companion);
+
+
+/*
+ * Display / Set uframe_periodic_max
+ */
+static ssize_t uframe_periodic_max_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct ehci_hcd		*ehci;
+
+	ehci = hcd_to_ehci(dev_get_drvdata(dev));
+	return sysfs_emit(buf, "%d\n", ehci->uframe_periodic_max);
+}
+
+
+static ssize_t uframe_periodic_max_store(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct ehci_hcd		*ehci;
+	unsigned		uframe_periodic_max;
+	unsigned		uframe;
+	unsigned long		flags;
+	ssize_t			ret;
+
+	ehci = hcd_to_ehci(dev_get_drvdata(dev));
+	if (kstrtouint(buf, 0, &uframe_periodic_max) < 0)
+		return -EINVAL;
+
+	if (uframe_periodic_max < 100 || uframe_periodic_max >= 125) {
+		ehci_info(ehci, "rejecting invalid request for "
+				"uframe_periodic_max=%u\n", uframe_periodic_max);
+		return -EINVAL;
+	}
+
+	ret = -EINVAL;
+
+	/*
+	 * lock, so that our checking does not race with possible periodic
+	 * bandwidth allocation through submitting new urbs.
+	 */
+	spin_lock_irqsave (&ehci->lock, flags);
+
+	/*
+	 * for request to decrease max periodic bandwidth, we have to check
+	 * to see whether the decrease is possible.
+	 */
+	if (uframe_periodic_max < ehci->uframe_periodic_max) {
+		u8		allocated_max = 0;
+
+		for (uframe = 0; uframe < EHCI_BANDWIDTH_SIZE; ++uframe)
+			allocated_max = max(allocated_max,
+					ehci->bandwidth[uframe]);
+
+		if (allocated_max > uframe_periodic_max) {
+			ehci_info(ehci,
+				"cannot decrease uframe_periodic_max because "
+				"periodic bandwidth is already allocated "
+				"(%u > %u)\n",
+				allocated_max, uframe_periodic_max);
+			goto out_unlock;
+		}
+	}
+
+	/* increasing is always ok */
+
+	ehci_info(ehci, "setting max periodic bandwidth to %u%% "
+			"(== %u usec/uframe)\n",
+			100*uframe_periodic_max/125, uframe_periodic_max);
+
+	if (uframe_periodic_max != 100)
+		ehci_warn(ehci, "max periodic bandwidth set is non-standard\n");
+
+	ehci->uframe_periodic_max = uframe_periodic_max;
+	ret = count;
+
+out_unlock:
+	spin_unlock_irqrestore (&ehci->lock, flags);
+	return ret;
+}
+static DEVICE_ATTR_RW(uframe_periodic_max);
+
+
+static inline int create_sysfs_files(struct ehci_hcd *ehci)
+{
+	struct device	*controller = ehci_to_hcd(ehci)->self.controller;
+	int	i = 0;
+
+	/* with integrated TT there is no companion! */
+	if (!ehci_is_TDI(ehci))
+		i = device_create_file(controller, &dev_attr_companion);
+	if (i)
+		goto out;
+
+	i = device_create_file(controller, &dev_attr_uframe_periodic_max);
+out:
+	return i;
+}
+
+static inline void remove_sysfs_files(struct ehci_hcd *ehci)
+{
+	struct device	*controller = ehci_to_hcd(ehci)->self.controller;
+
+	/* with integrated TT there is no companion! */
+	if (!ehci_is_TDI(ehci))
+		device_remove_file(controller, &dev_attr_companion);
+
+	device_remove_file(controller, &dev_attr_uframe_periodic_max);
+}