[PATCH 4.19 113/114] cfg80211: Use const more consistently in for_each_element macros

From: Greg Kroah-Hartman
Date: Thu Oct 10 2019 - 04:49:26 EST


From: Jouni Malinen <j@xxxxx>

commit 7388afe09143210f555bdd6c75035e9acc1fab96 upstream.

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@xxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/linux/ieee80211.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -3189,16 +3189,16 @@ 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) \
@@ -3235,7 +3235,7 @@ 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 */