wifi: mac80211: Fix overread in PREP frame processing

When the AF flag is enabled, hwmp_prep_frame_process() overreads orig_addr
by 2 bytes. Since this occurs within the socket buffer, it does not read
across memory boundaries and therefore poses no security risk; however, we
will fix it as a precaution.

In this fix, a new function mesh_path_parse_reply_frame() is established to
separate the implementation of frame format validation and the check for
unsupported features. This is intended to facilitate future work when
implementing the currently unsupported parts.

Assisted-by: Claude:Sonnet 4.6
Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
Link: https://patch.msgid.link/20260529230952.124754-5-masashi.honma@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/linux/ieee80211-mesh.h b/include/linux/ieee80211-mesh.h
index 8fbd31d9538d3242e91d1c55feda4205b48212d1..482ac0c6d759ce4063560363f5810ddaf88e96da 100644 (file)
--- a/include/linux/ieee80211-mesh.h
+++ b/include/linux/ieee80211-mesh.h
@@ -387,4 +387,20 @@ static inline bool ieee80211_mesh_preq_size_ok(const u8 *pos, u8 elen)
        return elen == needed;
 }
 
+/* IEEE Std 802.11-2016 9.4.2.114 PREP element */
+static inline bool ieee80211_mesh_prep_size_ok(const u8 *pos, u8 elen)
+{
+       u8 needed;
+
+       /* Check if the element contains flags */
+       needed = sizeof(struct ieee80211_mesh_hwmp_prep_top);
+       if (elen < needed)
+               return false;
+
+       needed += (ieee80211_mesh_preq_prep_ae_enabled(pos) ? ETH_ALEN : 0)
+                /* Target External Address */ +
+                sizeof(struct ieee80211_mesh_hwmp_prep_bottom);
+       return elen == needed;
+}
+
 #endif /* LINUX_IEEE80211_MESH_H */

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index ef6eff52f32a356b12f00a70326086d2cdf9daeb..f07e57d5568ae057fe7a2d54a105e34801df4ce9 100644 (file)
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -947,8 +947,8 @@ void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
                                                path_metric);
        }
        if (elems->prep) {
-               if (elems->prep_len != 31)
-                       /* Right now we support no AE */
+               /* Right now we do not support AE (Address Extension) */
+               if (ieee80211_mesh_preq_prep_ae_enabled(elems->prep))
                        goto free;
                path_metric = hwmp_route_info_get(sdata, mgmt, elems->prep,
                                                  MPATH_PREP);

diff --git a/net/mac80211/parse.c b/net/mac80211/parse.c
index 3d441ff9593d6682a8d248c281e7ba23096a1abd..97508b141b8cc4f965c63ef71f49d4314d1ca2d9 100644 (file)
--- a/net/mac80211/parse.c
+++ b/net/mac80211/parse.c
@@ -572,8 +572,13 @@ _ieee802_11_parse_elems_full(struct ieee80211_elems_parse_params *params,
                        }
                        break;
                case WLAN_EID_PREP:
-                       elems->prep = pos;
-                       elems->prep_len = elen;
+                       if (ieee80211_mesh_prep_size_ok(pos, elen)) {
+                               elems->prep = pos;
+                               elems->prep_len = elen;
+                       } else {
+                               elem_parse_failed =
+                                       IEEE80211_PARSE_ERR_BAD_ELEM_SIZE;
+                       }
                        break;
                case WLAN_EID_PERR:
                        elems->perr = pos;