bpf, devmap: Add missing RCU read lock on flush (86723c86) · Commits · 戴 / test

.ndo_xdp_xmit() assumes it is called under RCU. For example virtio_net uses RCU to detect it has setup the resources for tx. The assumption accidentally broke when introducing bulk queue in devmap. Fixes: ("bpf: devmap prepare xdp frames for bulking") Reported-by:

David Ahern <dsahern@gmail.com> Signed-off-by:

Toshiaki Makita <toshiaki.makita1@gmail.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/devmap.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -282,6 +282,7 @@ void __dev_map_flush(struct bpf_map *map)
		unsigned long *bitmap = this_cpu_ptr(dtab->flush_needed);
		u32 bit;

		rcu_read_lock();
		for_each_set_bit(bit, bitmap, map->max_entries) {
		struct bpf_dtab_netdev *dev = READ_ONCE(dtab->netdev_map[bit]);
		struct xdp_bulk_queue *bq;
		@@ -297,6 +298,7 @@ void __dev_map_flush(struct bpf_map *map)

		__clear_bit(bit, bitmap);
		}
		rcu_read_unlock();
		}

		/* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete and/or
		@@ -389,6 +391,7 @@ static void dev_map_flush_old(struct bpf_dtab_netdev *dev)

		int cpu;

		rcu_read_lock();
		for_each_online_cpu(cpu) {
		bitmap = per_cpu_ptr(dev->dtab->flush_needed, cpu);
		__clear_bit(dev->bit, bitmap);
		@@ -396,6 +399,7 @@ static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
		bq = per_cpu_ptr(dev->bulkq, cpu);
		bq_xmit_all(dev, bq, XDP_XMIT_FLUSH, false);
		}
		rcu_read_unlock();
		}
		}

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