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@google.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 *ifmsh) sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh); sband = ieee80211_get_sband(sdata); + if (!sband) + return -EINVAL; ie_len_he_cap = ieee80211_ie_len_he_cap(sdata); ie_len_eht_cap = ieee80211_ie_len_eht_cap(sdata); --