EUVD-2026-18770
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3Description
In the Linux kernel, the following vulnerability has been resolved: mac80211: fix crash in ieee80211_chan_bw_change for AP_VLAN stations ieee80211_chan_bw_change() iterates all stations and accesses link->reserved.oper via sta->sdata->link[link_id]. For stations on AP_VLAN interfaces (e.g. 4addr WDS clients), sta->sdata points to the VLAN sdata, whose link never participates in chanctx reservations. This leaves link->reserved.oper zero-initialized with chan == NULL, causing a NULL pointer dereference in __ieee80211_sta_cap_rx_bw() when accessing chandef->chan->band during CSA. Resolve the VLAN sdata to its parent AP sdata using get_bss_sdata() before accessing link data. [also change sta->sdata in ARRAY_SIZE even if it doesn't matter]
Analysis
Null pointer dereference in Linux kernel mac80211 IEEE 802.11 wireless subsystem crashes AP_VLAN stations during channel bandwidth change operations. The ieee80211_chan_bw_change() function incorrectly accesses link data on VLAN interfaces (such as 4-address WDS clients) where the link structure is uninitialized, leading to kernel panic when dereferencing a NULL channel pointer. …
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