mac80211: verify that skb data is present

A number of places in the mesh code don't check that
the frame data is present and in the skb header when
trying to access. Add those checks and the necessary
pskb_may_pull() calls. This prevents accessing data
that doesn't actually exist.

To do this, export ieee80211_get_mesh_hdrlen() to be
able to use it in mac80211.

Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 45a09de1ffe..2762e832998 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -309,7 +309,7 @@ unsigned int ieee80211_get_hdrlen_from_skb(const struct sk_buff *skb)
 }
 EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);
 
-static int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
+unsigned int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 {
         int ae = meshhdr->flags & MESH_FLAGS_AE;
         /* 802.11-2012, 8.2.4.7.3 */
@@ -323,6 +323,7 @@ static int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
                 return 18;
         }
 }
+EXPORT_SYMBOL(ieee80211_get_mesh_hdrlen);
 
 int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
                            enum nl80211_iftype iftype)