From: Jakub Sitnicki jakub@cloudflare.com
[ Upstream commit 0b2dc83906cf1e694e48003eae5df8fa63f76fd9 ]
We need to have a synchronize_rcu before free'ing the sockhash because any outstanding psock references will have a pointer to the map and when they use it, this could trigger a use after free.
This is a sister fix for sockhash, following commit 2bb90e5cc90e ("bpf: sockmap, synchronize_rcu before free'ing map") which addressed sockmap, which comes from a manual audit.
Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/bpf/20200206111652.694507-3-jakub@cloudflare.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/sock_map.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 8998e356f4232..058422b932607 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -250,6 +250,7 @@ static void sock_map_free(struct bpf_map *map) raw_spin_unlock_bh(&stab->lock); rcu_read_unlock();
+ /* wait for psock readers accessing its map link */ synchronize_rcu();
bpf_map_area_free(stab->sks); @@ -873,6 +874,9 @@ static void sock_hash_free(struct bpf_map *map) } rcu_read_unlock();
+ /* wait for psock readers accessing its map link */ + synchronize_rcu(); + bpf_map_area_free(htab->buckets); kfree(htab); }