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Date:   Fri, 14 Feb 2020 10:42:06 -0500
From:   Sasha Levin <>
Cc:     Jakub Sitnicki <>,
        Daniel Borkmann <>,
        John Fastabend <>,
        Sasha Levin <>,,
Subject: [PATCH AUTOSEL 5.5 134/542] bpf, sockhash: Synchronize_rcu before free'ing map

From: Jakub Sitnicki <>

[ 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 <>
Signed-off-by: Daniel Borkmann <>
Acked-by: John Fastabend <>
Signed-off-by: Sasha Levin <>
 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)
+	/* wait for psock readers accessing its map link */
@@ -873,6 +874,9 @@ static void sock_hash_free(struct bpf_map *map)
+	/* wait for psock readers accessing its map link */
+	synchronize_rcu();

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