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authorGrant Likely <grant.likely@linaro.org>2014-11-03 15:15:35 +0000
committerGrant Likely <grant.likely@linaro.org>2014-11-04 10:19:48 +0000
commita87fa1d81a9fb5e9adca9820e16008c40ad09f33 (patch)
treea6938084b9639c2aa54b3f7cc5fd0bebbbf3097d /drivers/of/base.c
parent0df1f2487d2f0d04703f142813d53615d62a1da4 (diff)
of: Fix overflow bug in string property parsing functions
The string property read helpers will run off the end of the buffer if it is handed a malformed string property. Rework the parsers to make sure that doesn't happen. At the same time add new test cases to make sure the functions behave themselves. The original implementations of of_property_read_string_index() and of_property_count_strings() both open-coded the same block of parsing code, each with it's own subtly different bugs. The fix here merges functions into a single helper and makes the original functions static inline wrappers around the helper. One non-bugfix aspect of this patch is the addition of a new wrapper, of_property_read_string_array(). The new wrapper is needed by the device_properties feature that Rafael is working on and planning to merge for v3.19. The implementation is identical both with and without the new static inline wrapper, so it just got left in to reduce the churn on the header file. Signed-off-by: Grant Likely <grant.likely@linaro.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: Rob Herring <robh+dt@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Darren Hart <darren.hart@intel.com> Cc: <stable@vger.kernel.org> # v3.3+: Drop selftest hunks that don't apply
Diffstat (limited to 'drivers/of/base.c')
-rw-r--r--drivers/of/base.c88
1 files changed, 22 insertions, 66 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)
{