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authorPatrick McHardy <kaber@trash.net>2008-06-18 02:07:07 -0700
committerDavid S. Miller <davem@davemloft.net>2008-06-18 02:07:07 -0700
commit6d1a3fb567a728d31474636e167c324702a0c38b (patch)
tree02ffcef1520345d44f080b821aa32f4a596b7e1f
parent3a5be7d4b079f3a9ce1e8ce4a93ba15ae6d00111 (diff)
netlink: genl: fix circular locking
genetlink has a circular locking dependency when dumping the registered families: - dump start: genl_rcv() : take genl_mutex genl_rcv_msg() : call netlink_dump_start() while holding genl_mutex netlink_dump_start(), netlink_dump() : take nlk->cb_mutex ctrl_dumpfamily() : try to detect this case and not take genl_mutex a second time - dump continuance: netlink_rcv() : call netlink_dump netlink_dump : take nlk->cb_mutex ctrl_dumpfamily() : take genl_mutex Register genl_lock as callback mutex with netlink to fix this. This slightly widens an already existing module unload race, the genl ops used during the dump might go away when the module is unloaded. Thomas Graf is working on a seperate fix for this. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/netlink/genetlink.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index f5aa23c3e886..3e1191cecaf0 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -444,8 +444,11 @@ static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
if (ops->dumpit == NULL)
return -EOPNOTSUPP;
- return netlink_dump_start(genl_sock, skb, nlh,
- ops->dumpit, ops->done);
+ genl_unlock();
+ err = netlink_dump_start(genl_sock, skb, nlh,
+ ops->dumpit, ops->done);
+ genl_lock();
+ return err;
}
if (ops->doit == NULL)
@@ -603,9 +606,6 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
int chains_to_skip = cb->args[0];
int fams_to_skip = cb->args[1];
- if (chains_to_skip != 0)
- genl_lock();
-
for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
if (i < chains_to_skip)
continue;
@@ -623,9 +623,6 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
}
errout:
- if (chains_to_skip != 0)
- genl_unlock();
-
cb->args[0] = i;
cb->args[1] = n;
@@ -770,7 +767,7 @@ static int __init genl_init(void)
/* we'll bump the group number right afterwards */
genl_sock = netlink_kernel_create(&init_net, NETLINK_GENERIC, 0,
- genl_rcv, NULL, THIS_MODULE);
+ genl_rcv, &genl_mutex, THIS_MODULE);
if (genl_sock == NULL)
panic("GENL: Cannot initialize generic netlink\n");