On Fri, 2017-02-10 at 09:49 -0800, Cong Wang wrote: > On Thu, Feb 9, 2017 at 7:23 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > > On Thu, 2017-02-09 at 19:19 -0800, Eric Dumazet wrote: > > > >> More likely the bug is in fanout_add(), with a buggy sequence in error > >> case, and not correct locking. > >> > >> kfree(po->rollover); > >> po->rollover = NULL; > >> > >> Two cpus entering fanout_add() (using the same af_packet socket, > >> syzkaller courtesy...) might both see po->fanout being NULL. > >> > >> Then they grab the mutex. Too late... > > > > Patch could be : > > > > For me, clearly the data structure that use-after-free'd is struct sock > rather than struct packet_rollover.
Fine. But your patch makes absolutely no sense.
