• D
    tuntap: Fix for a race in accessing numqueues · fa35864e
    Dominic Curran 提交于
    A patch for fixing a race between queue selection and changing queues
    was introduced in commit 92bb73ea("tuntap: fix a possible race between
    queue selection and changing queues").
    
    The fix was to prevent the driver from re-reading the tun->numqueues
    more than once within tun_select_queue() using ACCESS_ONCE().
    
    We have been experiancing 'Divide-by-zero' errors in tun_net_xmit()
    since we moved from 3.6 to 3.10, and believe that they come from a
    simular source where the value of tun->numqueues changes to zero
    between the first and a subsequent read of tun->numqueues.
    
    The fix is a simular use of ACCESS_ONCE(), as well as a multiply
    instead of a divide in the if statement.
    Signed-off-by: NDominic Curran <dominic.curran@citrix.com>
    Cc: Jason Wang <jasowang@redhat.com>
    Cc: Maxim Krasnyansky <maxk@qti.qualcomm.com>
    Acked-by: NJason Wang <jasowang@redhat.com>
    Acked-by: NMax Krasnyansky <maxk@kernel.org>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    fa35864e
tun.c 55.4 KB