[ 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: 5d053f9da431 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/devmap.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 357d456d57b9..fc500ca464d0 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -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(); } }