From: Jakub Sitnicki <jakub@cloudflare.com>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, kernel-team@cloudflare.com,
John Fastabend <john.fastabend@gmail.com>
Subject: [PATCH bpf 2/3] bpf, sockhash: synchronize_rcu before free'ing map
Date: Thu, 6 Feb 2020 12:16:51 +0100 [thread overview]
Message-ID: <20200206111652.694507-3-jakub@cloudflare.com> (raw)
In-Reply-To: <20200206111652.694507-1-jakub@cloudflare.com>
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>
---
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 fd8b426dbdf3..f36e13e577a3 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);
+ /* 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)
raw_spin_unlock_bh(&bucket->lock);
}
+ /* wait for psock readers accessing its map link */
+ synchronize_rcu();
+
bpf_map_area_free(htab->buckets);
kfree(htab);
}
--
2.24.1
next prev parent reply other threads:[~2020-02-06 11:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 11:16 [PATCH bpf 0/3] Fix locking order and synchronization on sockmap/sockhash tear-down Jakub Sitnicki
2020-02-06 11:16 ` [PATCH bpf 1/3] bpf, sockmap: Don't sleep while holding RCU lock on tear-down Jakub Sitnicki
2020-02-06 18:59 ` John Fastabend
2020-02-06 11:16 ` Jakub Sitnicki [this message]
2020-02-06 19:01 ` [PATCH bpf 2/3] bpf, sockhash: synchronize_rcu before free'ing map John Fastabend
2020-02-06 11:16 ` [PATCH bpf 3/3] selftests/bpf: Test freeing sockmap/sockhash with a socket in it Jakub Sitnicki
2020-02-06 19:03 ` John Fastabend
2020-02-09 2:41 ` Alexei Starovoitov
2020-02-09 4:12 ` Yonghong Song
2020-02-09 15:29 ` Jakub Sitnicki
2020-02-10 3:55 ` John Fastabend
2020-02-10 11:52 ` Jakub Sitnicki
2020-02-10 23:38 ` Daniel Borkmann
2020-02-06 19:43 ` [PATCH bpf 0/3] Fix locking order and synchronization on sockmap/sockhash tear-down John Fastabend
2020-02-07 10:45 ` Jakub Sitnicki
2020-03-10 16:44 ` John Fastabend
2020-03-11 11:51 ` Jakub Sitnicki
2020-03-10 11:30 ` Jakub Sitnicki
2020-02-07 21:56 ` Daniel Borkmann
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