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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jakub Sitnicki <jakub@cloudflare.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	John Fastabend <john.fastabend@gmail.com>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 5.4 115/459] bpf, sockhash: Synchronize_rcu before free'ing map
Date: Fri, 14 Feb 2020 10:56:05 -0500
Message-ID: <20200214160149.11681-115-sashal@kernel.org> (raw)
In-Reply-To: <20200214160149.11681-1-sashal@kernel.org>

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);
 }
-- 
2.20.1


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200214160149.11681-1-sashal@kernel.org>
2020-02-14 15:56 ` [PATCH AUTOSEL 5.4 114/459] bpftool: Don't crash on missing xlated program instructions Sasha Levin
2020-02-14 15:56 ` Sasha Levin [this message]
2020-02-14 15:56 ` [PATCH AUTOSEL 5.4 116/459] bpf, sockmap: Check update requirements after locking Sasha Levin
2020-02-14 15:56 ` [PATCH AUTOSEL 5.4 117/459] bpf: Improve bucket_log calculation logic Sasha Levin
2020-02-14 15:56 ` [PATCH AUTOSEL 5.4 118/459] bpf, sockmap: Don't sleep while holding RCU lock on tear-down Sasha Levin
2020-02-14 15:57 ` [PATCH AUTOSEL 5.4 186/459] samples/bpf: Set -fno-stack-protector when building BPF programs Sasha Levin
2020-02-14 15:57 ` [PATCH AUTOSEL 5.4 227/459] bpf: Print error message for bpftool cgroup show Sasha Levin
2020-02-14 15:58 ` [PATCH AUTOSEL 5.4 248/459] tools lib api fs: Fix gcc9 stringop-truncation compilation error Sasha Levin
2020-02-14 15:59 ` [PATCH AUTOSEL 5.4 307/459] bpf: Return -EBADRQC for invalid map type in __bpf_tx_xdp_map Sasha Levin
2020-02-14 16:00 ` [PATCH AUTOSEL 5.4 376/459] bpf, btf: Always output invariant hit in pahole DWARF to BTF transform Sasha Levin
2020-02-14 16:00 ` [PATCH AUTOSEL 5.4 397/459] selftests: bpf: Reset global state between reuseport test runs Sasha Levin
2020-02-14 16:01 ` [PATCH AUTOSEL 5.4 415/459] bpf: map_seq_next should always increase position index Sasha Levin
2020-02-14 16:01 ` [PATCH AUTOSEL 5.4 430/459] powerpc: Do not consider weak unresolved symbol relocations as bad Sasha Levin
2020-02-14 16:01 ` [PATCH AUTOSEL 5.4 455/459] i40e: Relax i40e_xsk_wakeup's return value when PF is busy Sasha Levin

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