From: Amol Grover frextrite@gmail.com
commit 485ec2ea9cf556e9c120e07961b7b459d776a115 upstream.
head is traversed using hlist_for_each_entry_rcu outside an RCU read-side critical section but under the protection of dtab->index_lock.
Hence, add corresponding lockdep expression to silence false-positive lockdep warnings, and harden RCU lists.
Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index") Signed-off-by: Amol Grover frextrite@gmail.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Jesper Dangaard Brouer brouer@redhat.com Acked-by: Toke Høiland-Jørgensen toke@redhat.com Link: https://lore.kernel.org/bpf/20200123120437.26506-1-frextrite@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/bpf/devmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -293,7 +293,8 @@ struct bpf_dtab_netdev *__dev_map_hash_l struct hlist_head *head = dev_map_index_hash(dtab, key); struct bpf_dtab_netdev *dev;
- hlist_for_each_entry_rcu(dev, head, index_hlist) + hlist_for_each_entry_rcu(dev, head, index_hlist, + lockdep_is_held(&dtab->index_lock)) if (dev->idx == key) return dev;