From: Willem de Bruijn <willemdebruijn.ker...@gmail.com> Date: Wed, 23 May 2018 14:29:52 -0400
> From: Willem de Bruijn <will...@google.com> > > A precondition check in ip_recv_error triggered on an otherwise benign > race. Remove the warning. > > The warning triggers when passing an ipv6 socket to this ipv4 error > handling function. RaceFuzzer was able to trigger it due to a race > in setsockopt IPV6_ADDRFORM. ... > This socket option converts a v6 socket that is connected to a v4 peer > to an v4 socket. It updates the socket on the fly, changing fields in > sk as well as other structs. This is inherently non-atomic. It races > with the lockless udp_recvmsg path. > > No other code makes an assumption that these fields are updated > atomically. It is benign here, too, as ip_recv_error cares only about > the protocol of the skbs enqueued on the error queue, for which > sk_family is not a precise predictor (thanks to another isue with > IPV6_ADDRFORM). > > Link: http://lkml.kernel.org/r/20180518120826.ga19...@dragonet.kaist.ac.kr > Fixes: ("7ce875e5ecb8 ipv4: warn once on passing AF_INET6 socket to > ip_recv_error") > Reported-by: DaeRyong Jeong <threeear...@gmail.com> > Suggested-by: Eric Dumazet <eduma...@google.com> > Signed-off-by: Willem de Bruijn <will...@google.com> Applied and queued up for -stable. The SHA1_ID doesn't go inside the (" ") of the Fixes tag, I fixed it up this time.
