From e6031f02269c0f51cf67886d177f02bc300b47cd Mon Sep 17 00:00:00 2001 From: Ivan Pustogarov Date: Thu, 3 Sep 2026 17:26:16 +0200 Subject: [PATCH] wifi: mac80211: avoid out-of-bounds read for empty PREQ elements ieee80211_mesh_preq_size_ok() derives the location of the PREQ bottom fields before checking whether the element contains even the fixed header. ieee80211_mesh_hwmp_preq_get_bottom() reads the flags byte to account for the optional Address Extension field. Consequently, an empty PREQ element causes a one-byte read beyond its declared payload. Move the helper call after both size checks, so the bottom fields are only accessed when they are present. Fixes: 8b40b1d24a60 ("wifi: mac80211: Fix overread in PREQ frame processing") Cc: stable@vger.kernel.org Signed-off-by: Ivan Pustogarov Link: https://patch.msgid.link/20260903152616.1646637-1-ivan@ipust.net Signed-off-by: Johannes Berg --- include/linux/ieee80211-mesh.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/ieee80211-mesh.h b/include/linux/ieee80211-mesh.h index 7eb15834531c..9e548b9173df 100644 --- a/include/linux/ieee80211-mesh.h +++ b/include/linux/ieee80211-mesh.h @@ -361,8 +361,7 @@ ieee80211_mesh_hwmp_perr_get_rcode(const u8 *ie, u8 dst_idx) /* IEEE Std 802.11-2016 9.4.2.113 PREQ element */ static inline bool ieee80211_mesh_preq_size_ok(const u8 *pos, u8 elen) { - struct ieee80211_mesh_hwmp_preq_bottom *preq_elem_bottom = - ieee80211_mesh_hwmp_preq_get_bottom(pos); + struct ieee80211_mesh_hwmp_preq_bottom *preq_elem_bottom; u8 target_count; int needed; @@ -378,6 +377,7 @@ static inline bool ieee80211_mesh_preq_size_ok(const u8 *pos, u8 elen) if (elen < needed) return false; + preq_elem_bottom = ieee80211_mesh_hwmp_preq_get_bottom(pos); target_count = preq_elem_bottom->target_count; /* IEEE Std 802.11-2016 Table 14-10 to 14-16 */ if (target_count < 1)