[PATCH AUTOSEL 5.2 026/123] bpf: sockmap, synchronize_rcu before free'ing map

Sasha Levin
2019-08-14T02:11:39Z

From: John Fastabend <john.fastabend@gmail.com>

[ Upstream commit 2bb90e5cc90e1d09f631aeab041a9cf913a5bbe5 ]

We need to have a synchronize_rcu before free'ing the sockmap because
any outstanding psock references will have a pointer to the map and
when they use this could trigger a use after free.

Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/sock_map.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 1d40e040320d2..bbc91597d8364 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -252,6 +252,8 @@ static void sock_map_free(struct bpf_map *map)
raw_spin_unlock_bh(&stab->lock);
rcu_read_unlock();

+ synchronize_rcu();
+
bpf_map_area_free(stab->sks);
kfree(stab);
}
--
2.20.1