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, 211 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/utstring.c b/drivers/acpi/acpica/utstring.c
new file mode 100644
index 000000000..aae71b8c5
--- /dev/null
+++ b/drivers/acpi/acpica/utstring.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/*******************************************************************************
+ *
+ * Module Name: utstring - Common functions for strings and characters
+ *
+ ******************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acnamesp.h"
+
+#define _COMPONENT          ACPI_UTILITIES
+ACPI_MODULE_NAME("utstring")
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_print_string
+ *
+ * PARAMETERS:  string          - Null terminated ASCII string
+ *              max_length      - Maximum output length. Used to constrain the
+ *                                length of strings during debug output only.
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Dump an ASCII string with support for ACPI-defined escape
+ *              sequences.
+ *
+ ******************************************************************************/
+void acpi_ut_print_string(char *string, u16 max_length)
+{
+	u32 i;
+
+	if (!string) {
+		acpi_os_printf("<\"NULL STRING PTR\">");
+		return;
+	}
+
+	acpi_os_printf("\"");
+	for (i = 0; (i < max_length) && string[i]; i++) {
+
+		/* Escape sequences */
+
+		switch (string[i]) {
+		case 0x07:
+
+			acpi_os_printf("\\a");	/* BELL */
+			break;
+
+		case 0x08:
+
+			acpi_os_printf("\\b");	/* BACKSPACE */
+			break;
+
+		case 0x0C:
+
+			acpi_os_printf("\\f");	/* FORMFEED */
+			break;
+
+		case 0x0A:
+
+			acpi_os_printf("\\n");	/* LINEFEED */
+			break;
+
+		case 0x0D:
+
+			acpi_os_printf("\\r");	/* CARRIAGE RETURN */
+			break;
+
+		case 0x09:
+
+			acpi_os_printf("\\t");	/* HORIZONTAL TAB */
+			break;
+
+		case 0x0B:
+
+			acpi_os_printf("\\v");	/* VERTICAL TAB */
+			break;
+
+		case '\'':	/* Single Quote */
+		case '\"':	/* Double Quote */
+		case '\\':	/* Backslash */
+
+			acpi_os_printf("\\%c", (int)string[i]);
+			break;
+
+		default:
+
+			/* Check for printable character or hex escape */
+
+			if (isprint((int)string[i])) {
+				/* This is a normal character */
+
+				acpi_os_printf("%c", (int)string[i]);
+			} else {
+				/* All others will be Hex escapes */
+
+				acpi_os_printf("\\x%2.2X", (s32)string[i]);
+			}
+			break;
+		}
+	}
+
+	acpi_os_printf("\"");
+
+	if (i == max_length && string[i]) {
+		acpi_os_printf("...");
+	}
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_repair_name
+ *
+ * PARAMETERS:  name            - The ACPI name to be repaired
+ *
+ * RETURN:      Repaired version of the name
+ *
+ * DESCRIPTION: Repair an ACPI name: Change invalid characters to '*' and
+ *              return the new name. NOTE: the Name parameter must reside in
+ *              read/write memory, cannot be a const.
+ *
+ * An ACPI Name must consist of valid ACPI characters. We will repair the name
+ * if necessary because we don't want to abort because of this, but we want
+ * all namespace names to be printable. A warning message is appropriate.
+ *
+ * This issue came up because there are in fact machines that exhibit
+ * this problem, and we want to be able to enable ACPI support for them,
+ * even though there are a few bad names.
+ *
+ ******************************************************************************/
+
+void acpi_ut_repair_name(char *name)
+{
+	u32 i;
+	u8 found_bad_char = FALSE;
+	u32 original_name;
+
+	ACPI_FUNCTION_NAME(ut_repair_name);
+
+	/*
+	 * Special case for the root node. This can happen if we get an
+	 * error during the execution of module-level code.
+	 */
+	if (ACPI_COMPARE_NAMESEG(name, ACPI_ROOT_PATHNAME)) {
+		return;
+	}
+
+	ACPI_COPY_NAMESEG(&original_name, &name[0]);
+
+	/* Check each character in the name */
+
+	for (i = 0; i < ACPI_NAMESEG_SIZE; i++) {
+		if (acpi_ut_valid_name_char(name[i], i)) {
+			continue;
+		}
+
+		/*
+		 * Replace a bad character with something printable, yet technically
+		 * "odd". This prevents any collisions with existing "good"
+		 * names in the namespace.
+		 */
+		name[i] = '_';
+		found_bad_char = TRUE;
+	}
+
+	if (found_bad_char) {
+
+		/* Report warning only if in strict mode or debug mode */
+
+		if (!acpi_gbl_enable_interpreter_slack) {
+			ACPI_WARNING((AE_INFO,
+				      "Invalid character(s) in name (0x%.8X) %p, repaired: [%4.4s]",
+				      original_name, name, &name[0]));
+		} else {
+			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+					  "Invalid character(s) in name (0x%.8X), repaired: [%4.4s]",
+					  original_name, name));
+		}
+	}
+}
+
+#if defined ACPI_ASL_COMPILER || defined ACPI_EXEC_APP
+/*******************************************************************************
+ *
+ * FUNCTION:    ut_convert_backslashes
+ *
+ * PARAMETERS:  pathname        - File pathname string to be converted
+ *
+ * RETURN:      Modifies the input Pathname
+ *
+ * DESCRIPTION: Convert all backslashes (0x5C) to forward slashes (0x2F) within
+ *              the entire input file pathname string.
+ *
+ ******************************************************************************/
+
+void ut_convert_backslashes(char *pathname)
+{
+
+	if (!pathname) {
+		return;
+	}
+
+	while (*pathname) {
+		if (*pathname == '\\') {
+			*pathname = '/';
+		}
+
+		pathname++;
+	}
+}
+#endif