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Hauke Mehrtens
d6c5598e2f
apup_process_beacon() dereferenced the return value of ap_sta_add()
without checking it. ap_sta_add() returns NULL when the station table is
full, when the allocation fails or when accounting_sta_get_id() fails,
so the following read of sta_ret->aid dereferences NULL.
The station table filling up is remotely triggerable. Beacons reach
handle_beacon() on every softmac driver, because hostapd subscribes to
them per wiphy with NL80211_CMD_REGISTER_BEACONS when it starts the AP.
An adjacent station can therefore beacon the target's SSID from
successive spoofed BSSIDs, each of which is added as an APuP peer, until
max_num_sta is reached and hostapd crashes.
CONFIG_APUP=y is set unconditionally in DRIVER_MAKEOPTS, so the code is
compiled into every wpad variant, but the call is gated on
hapd->conf->apup at runtime and wifi-scripts defaults apup to 0. Only
configurations that opt into APuP are affected.
Reported-by: JuliusBairaktaris
Fixes: e80520197c ("hostapd: Add support for APuP")
Assisted-by: Claude:claude-opus-5
Link: https://github.com/openwrt/openwrt/pull/25242
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>