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([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-81fa129199dsm9503402b3a.51.2026.01.19.07.02.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jan 2026 07:02:19 -0800 (PST) From: Jeongjun Park To: Johannes Berg Cc: linux-wireless@vger.kernel.org, syzbot+81cd9dc1596563141d19@syzkaller.appspotmail.com, linux-kernel@vger.kernel.org, Jeongjun Park Subject: [PATCH] wifi: mac80211: fix NULL pointer dereference in ieee80211_mesh_build_beacon() Date: Tue, 20 Jan 2026 00:00:31 +0900 Message-Id: <20260119150031.201832-1-aha310510@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" NULL pointer dereference bug occurs because ieee80211_mesh_build_beacon() does not check the return value of ieee80211_get_sband(). Therefore, we need to add a return value check to prevent this. Reported-by: syzbot+81cd9dc1596563141d19@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/696e34bf.a70a0220.34546f.04ad.GAE@googl= e.com/ Fixes: 147ceae20534 ("wifi: mac80211: simplify adding supported rates") Signed-off-by: Jeongjun Park --- net/mac80211/mesh.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c index 68901f1def0d..eb3a346226bd 100644 --- a/net/mac80211/mesh.c +++ b/net/mac80211/mesh.c @@ -964,6 +964,8 @@ ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *i= fmsh) sdata =3D container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh); =20 sband =3D ieee80211_get_sband(sdata); + if (!sband) + return -EINVAL; =20 ie_len_he_cap =3D ieee80211_ie_len_he_cap(sdata); ie_len_eht_cap =3D ieee80211_ie_len_eht_cap(sdata); --