• Ilpo Järvinen's avatar
    [TCP]: Fix fastpath_cnt_hint when GSO skb is partially ACKed · 48611c47
    Ilpo Järvinen authored
    When only GSO skb was partially ACKed, no hints are reset,
    therefore fastpath_cnt_hint must be tweaked too or else it can
    corrupt fackets_out. The corruption to occur, one must have
    non-trivial ACK/SACK sequence, so this bug is not very often
    that harmful. There's a fackets_out state reset in TCP because
    fackets_out is known to be inaccurate and that fixes the issue
    eventually anyway.
    
    In case there was also at least one skb that got fully ACKed,
    the fastpath_skb_hint is set to NULL which causes a recount for
    fastpath_cnt_hint (the old value won't be accessed anymore),
    thus it can safely be decremented without additional checking.
    
    Reported by Cedric Le Goater <clg@fr.ibm.com>
    Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    48611c47
tcp_input.c 141 KB