Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4c2ce7ad authored by Toshiaki Makita's avatar Toshiaki Makita Committed by Greg Kroah-Hartman
Browse files

bpf, devmap: Add missing RCU read lock on flush 



[ Upstream commit 86723c8640633bee4b4588d3c7784ee7a0032f65 ]

.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: 5d053f9d ("bpf: devmap prepare xdp frames for bulking")
Reported-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarToshiaki Makita <toshiaki.makita1@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent ab44f8bc

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();

	}

}