cfg80211: Use const more consistently in for_each_element macros

Enforce the first argument to be a correct type of a pointer to struct
element and avoid unnecessary typecasts from const to non-const pointers
(the change in validate_ie_attr() is needed to make this part work). In
addition, avoid signed/unsigned comparison within for_each_element() and
mark struct element packed just in case.

Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 3c9dfca..6cbaed4 100644 (file)
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -3284,16 +3284,16 @@ struct element {
        u8 id;
        u8 datalen;
        u8 data[];
-};
+} __packed;
 
 /* element iteration helpers */
-#define for_each_element(element, _data, _datalen)                     \
-       for (element = (void *)(_data);                                 \
-            (u8 *)(_data) + (_datalen) - (u8 *)element >=              \
-               sizeof(*element) &&                                     \
-            (u8 *)(_data) + (_datalen) - (u8 *)element >=              \
-               sizeof(*element) + element->datalen;                    \
-            element = (void *)(element->data + element->datalen))
+#define for_each_element(_elem, _data, _datalen)                       \
+       for (_elem = (const struct element *)(_data);                   \
+            (const u8 *)(_data) + (_datalen) - (const u8 *)_elem >=    \
+               (int)sizeof(*_elem) &&                                  \
+            (const u8 *)(_data) + (_datalen) - (const u8 *)_elem >=    \
+               (int)sizeof(*_elem) + _elem->datalen;                   \
+            _elem = (const struct element *)(_elem->data + _elem->datalen))
 
 #define for_each_element_id(element, _id, data, datalen)               \
        for_each_element(element, data, datalen)                        \
@@ -3330,7 +3330,7 @@ struct element {
 static inline bool for_each_element_completed(const struct element *element,
                                              const void *data, size_t datalen)
 {
-       return (u8 *)element == (u8 *)data + datalen;
+       return (const u8 *)element == (const u8 *)data + datalen;
 }
 
 #endif /* LINUX_IEEE80211_H */

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 5d85f60..80878b4 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -205,7 +205,7 @@ static int validate_ie_attr(const struct nlattr *attr,
 {
        const u8 *data = nla_data(attr);
        unsigned int len = nla_len(attr);
-       struct element *elem;
+       const struct element *elem;
 
        for_each_element(elem, data, len) {
                /* nothing */