Merge branch 'devicetree/merge' of git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux

Pull devicetree bugfix from Grant Likely:
 "One buffer overflow bug that shouldn't be left around"

* 'devicetree/merge' of git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux:
  of: Fix overflow bug in string property parsing functions

3 files changed, 84 insertions, 72 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 2305dc0382bc..3823edf2d012 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1280,52 +1280,6 @@ int of_property_read_string(struct device_node *np, const char *propname,
 EXPORT_SYMBOL_GPL(of_property_read_string);
 
 /**
- * of_property_read_string_index - Find and read a string from a multiple
- * strings property.
- * @np:		device node from which the property value is to be read.
- * @propname:	name of the property to be searched.
- * @index:	index of the string in the list of strings
- * @out_string:	pointer to null terminated return string, modified only if
- *		return value is 0.
- *
- * Search for a property in a device tree node and retrieve a null
- * terminated string value (pointer to data, not a copy) in the list of strings
- * contained in that property.
- * Returns 0 on success, -EINVAL if the property does not exist, -ENODATA if
- * property does not have a value, and -EILSEQ if the string is not
- * null-terminated within the length of the property data.
- *
- * The out_string pointer is modified only if a valid string can be decoded.
- */
-int of_property_read_string_index(struct device_node *np, const char *propname,
-				  int index, const char **output)
-{
-	struct property *prop = of_find_property(np, propname, NULL);
-	int i = 0;
-	size_t l = 0, total = 0;
-	const char *p;
-
-	if (!prop)
-		return -EINVAL;
-	if (!prop->value)
-		return -ENODATA;
-	if (strnlen(prop->value, prop->length) >= prop->length)
-		return -EILSEQ;
-
-	p = prop->value;
-
-	for (i = 0; total < prop->length; total += l, p += l) {
-		l = strlen(p) + 1;
-		if (i++ == index) {
-			*output = p;
-			return 0;
-		}
-	}
-	return -ENODATA;
-}
-EXPORT_SYMBOL_GPL(of_property_read_string_index);
-
-/**
  * of_property_match_string() - Find string in a list and return index
  * @np: pointer to node containing string list property
  * @propname: string list property name
@@ -1351,7 +1305,7 @@ int of_property_match_string(struct device_node *np, const char *propname,
 	end = p + prop->length;
 
 	for (i = 0; p < end; i++, p += l) {
-		l = strlen(p) + 1;
+		l = strnlen(p, end - p) + 1;
 		if (p + l > end)
 			return -EILSEQ;
 		pr_debug("comparing %s with %s\n", string, p);
@@ -1363,39 +1317,41 @@ int of_property_match_string(struct device_node *np, const char *propname,
 EXPORT_SYMBOL_GPL(of_property_match_string);
 
 /**
- * of_property_count_strings - Find and return the number of strings from a
- * multiple strings property.
+ * of_property_read_string_util() - Utility helper for parsing string properties
  * @np:		device node from which the property value is to be read.
  * @propname:	name of the property to be searched.
+ * @out_strs:	output array of string pointers.
+ * @sz:		number of array elements to read.
+ * @skip:	Number of strings to skip over at beginning of list.
  *
- * Search for a property in a device tree node and retrieve the number of null
- * terminated string contain in it. Returns the number of strings on
- * success, -EINVAL if the property does not exist, -ENODATA if property
- * does not have a value, and -EILSEQ if the string is not null-terminated
- * within the length of the property data.
+ * Don't call this function directly. It is a utility helper for the
+ * of_property_read_string*() family of functions.
  */
-int of_property_count_strings(struct device_node *np, const char *propname)
+int of_property_read_string_helper(struct device_node *np, const char *propname,
+				   const char **out_strs, size_t sz, int skip)
 {
 	struct property *prop = of_find_property(np, propname, NULL);
-	int i = 0;
-	size_t l = 0, total = 0;
-	const char *p;
+	int l = 0, i = 0;
+	const char *p, *end;
 
 	if (!prop)
 		return -EINVAL;
 	if (!prop->value)
 		return -ENODATA;
-	if (strnlen(prop->value, prop->length) >= prop->length)
-		return -EILSEQ;
-
 	p = prop->value;
+	end = p + prop->length;
 
-	for (i = 0; total < prop->length; total += l, p += l, i++)
-		l = strlen(p) + 1;
-
-	return i;
+	for (i = 0; p < end && (!out_strs || i < skip + sz); i++, p += l) {
+		l = strnlen(p, end - p) + 1;
+		if (p + l > end)
+			return -EILSEQ;
+		if (out_strs && i >= skip)
+			*out_strs++ = p;
+	}
+	i -= skip;
+	return i <= 0 ? -ENODATA : i;
 }
-EXPORT_SYMBOL_GPL(of_property_count_strings);
+EXPORT_SYMBOL_GPL(of_property_read_string_helper);
 
 void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
 {
diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c
index 78001270a598..11b873c54a77 100644
--- a/drivers/of/selftest.c
+++ b/drivers/of/selftest.c
@@ -339,8 +339,9 @@ static void __init of_selftest_parse_phandle_with_args(void)
 	selftest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
 }
 
-static void __init of_selftest_property_match_string(void)
+static void __init of_selftest_property_string(void)
 {
+	const char *strings[4];
 	struct device_node *np;
 	int rc;
 
@@ -357,13 +358,66 @@ static void __init of_selftest_property_match_string(void)
 	rc = of_property_match_string(np, "phandle-list-names", "third");
 	selftest(rc == 2, "third expected:0 got:%i\n", rc);
 	rc = of_property_match_string(np, "phandle-list-names", "fourth");
-	selftest(rc == -ENODATA, "unmatched string; rc=%i", rc);
+	selftest(rc == -ENODATA, "unmatched string; rc=%i\n", rc);
 	rc = of_property_match_string(np, "missing-property", "blah");
-	selftest(rc == -EINVAL, "missing property; rc=%i", rc);
+	selftest(rc == -EINVAL, "missing property; rc=%i\n", rc);
 	rc = of_property_match_string(np, "empty-property", "blah");
-	selftest(rc == -ENODATA, "empty property; rc=%i", rc);
+	selftest(rc == -ENODATA, "empty property; rc=%i\n", rc);
 	rc = of_property_match_string(np, "unterminated-string", "blah");
-	selftest(rc == -EILSEQ, "unterminated string; rc=%i", rc);
+	selftest(rc == -EILSEQ, "unterminated string; rc=%i\n", rc);
+
+	/* of_property_count_strings() tests */
+	rc = of_property_count_strings(np, "string-property");
+	selftest(rc == 1, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_count_strings(np, "phandle-list-names");
+	selftest(rc == 3, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_count_strings(np, "unterminated-string");
+	selftest(rc == -EILSEQ, "unterminated string; rc=%i\n", rc);
+	rc = of_property_count_strings(np, "unterminated-string-list");
+	selftest(rc == -EILSEQ, "unterminated string array; rc=%i\n", rc);
+
+	/* of_property_read_string_index() tests */
+	rc = of_property_read_string_index(np, "string-property", 0, strings);
+	selftest(rc == 0 && !strcmp(strings[0], "foobar"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "string-property", 1, strings);
+	selftest(rc == -ENODATA && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "phandle-list-names", 0, strings);
+	selftest(rc == 0 && !strcmp(strings[0], "first"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "phandle-list-names", 1, strings);
+	selftest(rc == 0 && !strcmp(strings[0], "second"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "phandle-list-names", 2, strings);
+	selftest(rc == 0 && !strcmp(strings[0], "third"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "phandle-list-names", 3, strings);
+	selftest(rc == -ENODATA && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "unterminated-string", 0, strings);
+	selftest(rc == -EILSEQ && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "unterminated-string-list", 0, strings);
+	selftest(rc == 0 && !strcmp(strings[0], "first"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "unterminated-string-list", 2, strings); /* should fail */
+	selftest(rc == -EILSEQ && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[1] = NULL;
+
+	/* of_property_read_string_array() tests */
+	rc = of_property_read_string_array(np, "string-property", strings, 4);
+	selftest(rc == 1, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_read_string_array(np, "phandle-list-names", strings, 4);
+	selftest(rc == 3, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_read_string_array(np, "unterminated-string", strings, 4);
+	selftest(rc == -EILSEQ, "unterminated string; rc=%i\n", rc);
+	/* -- An incorrectly formed string should cause a failure */
+	rc = of_property_read_string_array(np, "unterminated-string-list", strings, 4);
+	selftest(rc == -EILSEQ, "unterminated string array; rc=%i\n", rc);
+	/* -- parsing the correctly formed strings should still work: */
+	strings[2] = NULL;
+	rc = of_property_read_string_array(np, "unterminated-string-list", strings, 2);
+	selftest(rc == 2 && strings[2] == NULL, "of_property_read_string_array() failure; rc=%i\n", rc);
+	strings[1] = NULL;
+	rc = of_property_read_string_array(np, "phandle-list-names", strings, 1);
+	selftest(rc == 1 && strings[1] == NULL, "Overwrote end of string array; rc=%i, str='%s'\n", rc, strings[1]);
 }
 
 #define propcmp(p1, p2) (((p1)->length == (p2)->length) && \
@@ -881,7 +935,7 @@ static int __init of_selftest(void)
 	of_selftest_find_node_by_name();
 	of_selftest_dynamic();
 	of_selftest_parse_phandle_with_args();
-	of_selftest_property_match_string();
+	of_selftest_property_string();
 	of_selftest_property_copy();
 	of_selftest_changeset();
 	of_selftest_parse_interrupts();
diff --git a/drivers/of/testcase-data/tests-phandle.dtsi b/drivers/of/testcase-data/tests-phandle.dtsi
index ce0fe083d406..5b1527e8a7fb 100644
--- a/drivers/of/testcase-data/tests-phandle.dtsi
+++ b/drivers/of/testcase-data/tests-phandle.dtsi
@@ -39,7 +39,9 @@
 				phandle-list-bad-args = <&provider2 1 0>,
 							<&provider3 0>;
 				empty-property;
+				string-property = "foobar";
 				unterminated-string = [40 41 42 43];
+				unterminated-string-list = "first", "second", [40 41 42 43];
 			};
 		};
 	};