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Date: Fri, 14 Feb 2020 10:42:06 -0500 From: Sasha Levin <sashal@...nel.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Jakub Sitnicki <jakub@...udflare.com>, Daniel Borkmann <daniel@...earbox.net>, John Fastabend <john.fastabend@...il.com>, Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org, bpf@...r.kernel.org Subject: [PATCH AUTOSEL 5.5 134/542] bpf, sockhash: Synchronize_rcu before free'ing map From: Jakub Sitnicki <jakub@...udflare.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@...udflare.com> Signed-off-by: Daniel Borkmann <daniel@...earbox.net> Acked-by: John Fastabend <john.fastabend@...il.com> Link: https://lore.kernel.org/bpf/20200206111652.694507-3-jakub@cloudflare.com Signed-off-by: Sasha Levin <sashal@...nel.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); } -- 2.20.1
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