Commmit 58ad436fcf49810aa006016107f494c9ac9013db
Author: Johannes Berg <johannes.berg at intel.com>
genetlink: fix family dump race
added genl_lock() call to ctrl_dumpfamily(), which potentially
can deadlock. Suppose the following case:
genl_rcv_msg(): !family->parallel_ops -> genl_lock()
genl_family_rcv_msg()
netlink_dump_start()
netlink_dump()
ctrl_dumpfamily() --> genl_lock()
Take in account possibility of genl_lock() in genl_rcv_msg() and do
not acquire genl_mutex in ctrl_dumpfamily() for a family that supports
parallel_ops.
Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
---
net/netlink/genetlink.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index f85f8a2..fca3659 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -791,6 +791,12 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct
netlink_callback *cb)
int fams_to_skip = cb->args[1];
bool need_locking = chains_to_skip || fams_to_skip;
+ if (need_locking) {
+ /* genl_mutex could be already locked in genl_rcv_msg() */
+ rt = genl_family_find_byid(cb->nlh->nlmsg_type);
+ need_locking = need_locking && rt->parallel_ops;
+ }
+
if (need_locking)
genl_lock();
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
