On Thu, Oct 24, 2019 at 5:53 AM Magnus Karlsson <magnus.karlsson@xxxxxxxxx> wrote: > > On Thu, Oct 24, 2019 at 12:47 PM Jonathan Lemon > <jonathan.lemon@xxxxxxxxx> wrote: > > > > On 21 Oct 2019, at 1:16, Magnus Karlsson wrote: > > > > > Having Rx-only AF_XDP sockets can potentially lead to a crash in the > > > system by a NULL pointer dereference in xsk_umem_consume_tx(). This > > > function iterates through a list of all sockets tied to a umem and > > > checks if there are any packets to send on the Tx ring. Rx-only > > > sockets do not have a Tx ring, so this will cause a NULL pointer > > > dereference. This will happen if you have registered one or more > > > Rx-only sockets to a umem and the driver is checking the Tx ring even > > > on Rx, or if the XDP_SHARED_UMEM mode is used and there is a mix of > > > Rx-only and other sockets tied to the same umem. > > > > > > Fixed by only putting sockets with a Tx component on the list that > > > xsk_umem_consume_tx() iterates over. > > > > A future improvement might be renaming umem->xsk_list to umem->xsk_tx_list > > or similar, in order to make it clear that the list is only used on the > > TX path. > > Agreed. Had that exact name in my first internal version of the patch > :-), but that rename touched a lot of places so it obfuscated the fix > and therefore I removed it to make it clearer. But I can submit a > patch with the rename to bpf-next. please do so after bpf fixes will travel to net->linus->net-next->bpf-next Dealing with merge conflicts is not worth it otherwise.
