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.
