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| author | Herbert Xu <herbert@gondor.apana.org.au> | 2015-09-18 19:16:50 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-09-20 22:55:31 -0700 |
| commit | 1f770c0a09da855a2b51af6d19de97fb955eca85 (patch) | |
| tree | eeb43c3ce6917390ce6e55b48990d2ba32aaf9cc /net | |
| parent | 3ea79249e81e5ed051f2e6480cbde896d99046e8 (diff) | |
| download | linux-1f770c0a09da855a2b51af6d19de97fb955eca85.tar.gz linux-1f770c0a09da855a2b51af6d19de97fb955eca85.tar.bz2 linux-1f770c0a09da855a2b51af6d19de97fb955eca85.zip | |
netlink: Fix autobind race condition that leads to zero port ID
The commit c0bb07df7d981e4091432754e30c9c720e2c0c78 ("netlink:
Reset portid after netlink_insert failure") introduced a race
condition where if two threads try to autobind the same socket
one of them may end up with a zero port ID. This led to kernel
deadlocks that were observed by multiple people.
This patch reverts that commit and instead fixes it by introducing
a separte rhash_portid variable so that the real portid is only set
after the socket has been successfully hashed.
Fixes: c0bb07df7d98 ("netlink: Reset portid after netlink_insert failure")
Reported-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netlink/af_netlink.c | 12 | ||||
| -rw-r--r-- | net/netlink/af_netlink.h | 1 |
2 files changed, 8 insertions, 5 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 4cad99d6c68b..9f51608b968a 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1031,7 +1031,7 @@ static inline int netlink_compare(struct rhashtable_compare_arg *arg, const struct netlink_compare_arg *x = arg->key; const struct netlink_sock *nlk = ptr; - return nlk->portid != x->portid || + return nlk->rhash_portid != x->portid || !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet)); } @@ -1057,7 +1057,7 @@ static int __netlink_insert(struct netlink_table *table, struct sock *sk) { struct netlink_compare_arg arg; - netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid); + netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->rhash_portid); return rhashtable_lookup_insert_key(&table->hash, &arg, &nlk_sk(sk)->node, netlink_rhashtable_params); @@ -1119,7 +1119,7 @@ static int netlink_insert(struct sock *sk, u32 portid) unlikely(atomic_read(&table->hash.nelems) >= UINT_MAX)) goto err; - nlk_sk(sk)->portid = portid; + nlk_sk(sk)->rhash_portid = portid; sock_hold(sk); err = __netlink_insert(table, sk); @@ -1131,10 +1131,12 @@ static int netlink_insert(struct sock *sk, u32 portid) err = -EOVERFLOW; if (err == -EEXIST) err = -EADDRINUSE; - nlk_sk(sk)->portid = 0; sock_put(sk); + goto err; } + nlk_sk(sk)->portid = portid; + err: release_sock(sk); return err; @@ -3271,7 +3273,7 @@ static inline u32 netlink_hash(const void *data, u32 len, u32 seed) const struct netlink_sock *nlk = data; struct netlink_compare_arg arg; - netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid); + netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->rhash_portid); return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed); } diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h index df9a06090db6..80b2b7526dfd 100644 --- a/net/netlink/af_netlink.h +++ b/net/netlink/af_netlink.h @@ -25,6 +25,7 @@ struct netlink_ring { struct netlink_sock { /* struct sock has to be the first member of netlink_sock */ struct sock sk; + u32 rhash_portid; u32 portid; u32 dst_portid; u32 dst_group; |