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| author | Eric Dumazet <edumazet@google.com> | 2020-06-30 16:41:01 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-07-22 09:10:48 +0200 |
| commit | d9e26f65ff4b174a7b8afdb98941e14ab88503e3 (patch) | |
| tree | f3169a5383608e961058d3a2721c1e0508c716b6 /net | |
| parent | e5ba276fac94282a0e75fafd539001a2fa5a3f45 (diff) | |
| download | linux-d9e26f65ff4b174a7b8afdb98941e14ab88503e3.tar.gz linux-d9e26f65ff4b174a7b8afdb98941e14ab88503e3.tar.bz2 linux-d9e26f65ff4b174a7b8afdb98941e14ab88503e3.zip | |
tcp: md5: add missing memory barriers in tcp_md5_do_add()/tcp_md5_hash_key()
[ Upstream commit 6a2febec338df7e7699a52d00b2e1207dcf65b28 ]
MD5 keys are read with RCU protection, and tcp_md5_do_add()
might update in-place a prior key.
Normally, typical RCU updates would allocate a new piece
of memory. In this case only key->key and key->keylen might
be updated, and we do not care if an incoming packet could
see the old key, the new one, or some intermediate value,
since changing the key on a live flow is known to be problematic
anyway.
We only want to make sure that in the case key->keylen
is changed, cpus in tcp_md5_hash_key() wont try to use
uninitialized data, or crash because key->keylen was
read twice to feed sg_init_one() and ahash_request_set_crypt()
Fixes: 9ea88a153001 ("tcp: md5: check md5 signature without socket lock")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 7 | ||||
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 3 |
2 files changed, 8 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 02918e0d635e..4791242be25b 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3207,10 +3207,13 @@ EXPORT_SYMBOL(tcp_md5_hash_skb_data); int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key) { + u8 keylen = key->keylen; struct scatterlist sg; - sg_init_one(&sg, key->key, key->keylen); - ahash_request_set_crypt(hp->md5_req, &sg, NULL, key->keylen); + smp_rmb(); /* paired with smp_wmb() in tcp_md5_do_add() */ + + sg_init_one(&sg, key->key, keylen); + ahash_request_set_crypt(hp->md5_req, &sg, NULL, keylen); return crypto_ahash_update(hp->md5_req); } EXPORT_SYMBOL(tcp_md5_hash_key); diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index e1cf810140b0..5001a922fc55 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -938,6 +938,9 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, if (key) { /* Pre-existing entry - just update that one. */ memcpy(key->key, newkey, newkeylen); + + smp_wmb(); /* pairs with smp_rmb() in tcp_md5_hash_key() */ + key->keylen = newkeylen; return 0; } |