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Felix Fietkau
1920d6dc68
mt7915_remove_interface() cleared the wcid mask bit with no lock held and
before clearing the RCU wcid pointer. The mask is a non-atomic RMW shared
with the allocators, which all run under dev->mt76.mutex; on DBDC the two
wiphys share one mt76_dev, so this raced add_interface/sta_add on the
other band and could leak or double-hand-out a wcid. Clearing the bit
before the RCU pointer also let a concurrent allocation reuse the index
and publish its wcid, which the subsequent NULL assignment then wiped.
Move the clear into the existing mutex section, after the RCU pointer is
cleared.
Fixes: f3049b88b2b3 ("wifi: mt76: mt7915: allocate vif wcid in the same range as stations")
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>