From: Thomas Graf Date: Wed, 6 Aug 2014 23:18:47 +0000 (+0100) Subject: netlink: hold nl_sock_hash_lock during diag dump X-Git-Tag: v3.17-rc1~95^2 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=6c8f7e70837468da4e658080d4448930fb597e1b;p=~emulex%2Finfiniband.git netlink: hold nl_sock_hash_lock during diag dump Although RCU protection would be possible during diag dump, doing so allows for concurrent table mutations which can render the in-table offset between individual Netlink messages invalid and thus cause legitimate sockets to be skipped in the dump. Since the diag dump is relatively low volume and consistency is more important than performance, the table mutex is held during dump. Reported-by: Andrey Wagin Signed-off-by: Thomas Graf Fixes: e341694e3eb57fc ("netlink: Convert netlink_lookup() to use RCU protected hash table") Signed-off-by: David S. Miller --- diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 479a344563d..a324b4b34c9 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -104,6 +104,7 @@ static atomic_t nl_table_users = ATOMIC_INIT(0); /* Protects netlink socket hash table mutations */ DEFINE_MUTEX(nl_sk_hash_lock); +EXPORT_SYMBOL_GPL(nl_sk_hash_lock); static int lockdep_nl_sk_hash_is_held(void) { diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h index 60f631fb708..b20a1731759 100644 --- a/net/netlink/af_netlink.h +++ b/net/netlink/af_netlink.h @@ -73,5 +73,6 @@ struct netlink_table { extern struct netlink_table *nl_table; extern rwlock_t nl_table_lock; +extern struct mutex nl_sk_hash_lock; #endif diff --git a/net/netlink/diag.c b/net/netlink/diag.c index 7301850eb56..de8c74a3c06 100644 --- a/net/netlink/diag.c +++ b/net/netlink/diag.c @@ -170,6 +170,7 @@ static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) req = nlmsg_data(cb->nlh); + mutex_lock(&nl_sk_hash_lock); read_lock(&nl_table_lock); if (req->sdiag_protocol == NDIAG_PROTO_ALL) { @@ -183,6 +184,7 @@ static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) } else { if (req->sdiag_protocol >= MAX_LINKS) { read_unlock(&nl_table_lock); + mutex_unlock(&nl_sk_hash_lock); return -ENOENT; } @@ -190,6 +192,7 @@ static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) } read_unlock(&nl_table_lock); + mutex_unlock(&nl_sk_hash_lock); return skb->len; }