tcp: md5: add missing memory barriers in tcp_md5_do_add()/tcp_md5_hash_key()
[ Upstream commit6a2febec33
] 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:9ea88a1530
("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>
This commit is contained in:
parent
f52293aefe
commit
1c8bad567b
|
@ -3847,10 +3847,13 @@ 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);
|
||||
|
|
|
@ -1079,6 +1079,9 @@ 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;
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue