mac80211: always allocate struct ieee802_11_elems

As the 802.11 spec evolves, we need to parse more and more
elements. This is causing the struct to grow, and we can no
longer get away with putting it on the stack.

Change the API to always dynamically allocate and return an
allocated pointer that must be kfree()d later.

As an alternative, I contemplated a scheme whereby we'd say
in the code which elements we needed, e.g.

    DECLARE_ELEMENT_PARSER(elems,
                           SUPPORTED_CHANNELS,
                           CHANNEL_SWITCH,
                           EXT(KEY_DELIVERY));

    ieee802_11_parse_elems(..., &elems, ...);

and while I think this is possible and will save us a lot
since most individual places only care about a small subset
of the elements, it ended up being a bit more work since a
lot of places do the parsing and then pass the struct to
other functions, sometimes with multiple levels.

Link: https://lore.kernel.org/r/20210920154009.26caff6b5998.I05ae58768e990e611aee8eca8abefd9d7bc15e05@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 11 insertions, 11 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 7a9e529f8366..c3b8590a7e90 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -2192,18 +2192,18 @@ static inline void ieee80211_tx_skb(struct ieee80211_sub_if_data *sdata,
 	ieee80211_tx_skb_tid(sdata, skb, 7);
 }
 
-void ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
-				struct ieee802_11_elems *elems,
-				u64 filter, u32 crc, u8 *transmitter_bssid,
-				u8 *bss_bssid);
-static inline void ieee802_11_parse_elems(const u8 *start, size_t len,
-					  bool action,
-					  struct ieee802_11_elems *elems,
-					  u8 *transmitter_bssid,
-					  u8 *bss_bssid)
+struct ieee802_11_elems *ieee802_11_parse_elems_crc(const u8 *start, size_t len,
+						    bool action,
+						    u64 filter, u32 crc,
+						    const u8 *transmitter_bssid,
+						    const u8 *bss_bssid);
+static inline struct ieee802_11_elems *
+ieee802_11_parse_elems(const u8 *start, size_t len, bool action,
+		       const u8 *transmitter_bssid,
+		       const u8 *bss_bssid)
 {
-	ieee802_11_parse_elems_crc(start, len, action, elems, 0, 0,
-				   transmitter_bssid, bss_bssid);
+	return ieee802_11_parse_elems_crc(start, len, action, 0, 0,
+					  transmitter_bssid, bss_bssid);
 }