• Michal Kazior's avatar
    ath10k: workaround fw beaconing bug · 64badcb6
    Michal Kazior authored
    Some firmware revisions don't wait for beacon tx
    completion before sending another SWBA event. This
    could lead to hardware using old (freed) beacon
    data in some cases, e.g. tx credit starvation
    combined with missed TBTT. This is very very rare.
    
    On non-IOMMU-enabled hosts this could be a
    possible security issue because hw could beacon
    some random data on the air.  On IOMMU-enabled
    hosts DMAR faults would occur in most cases and
    target device would crash.
    
    Since there are no beacon tx completions (implicit
    nor explicit) propagated to host the only
    workaround for this is to allocate a DMA-coherent
    buffer for a lifetime of a vif and use it for all
    beacon tx commands. Worst case for this approach
    is some beacons may become corrupted, e.g. garbled
    IEs or out-of-date TIM bitmap.
    
    Keep the original beacon-related code as-is in
    case future firmware revisions solve this problem
    so that the old path can be easily re-enabled with
    a fw_feature flag.
    Signed-off-by: default avatarMichal Kazior <michal.kazior@tieto.com>
    Signed-off-by: default avatarKalle Valo <kvalo@qca.qualcomm.com>
    64badcb6
mac.c 122 KB