On Fri, 2017-02-10 at 09:59 -0800, Eric Dumazet wrote: > 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.
At least, Anoob patch is making a step into the right direction ;) https://patchwork.ozlabs.org/patch/726532/