This is a note to let you know that I've just added the patch titled
genetlink: hold read cb_lock during iteration of genl_fam_idr in genl_bind()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
genetlink-hold-read-cb_lock-during-iteration-of-genl.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 15530c236059ca932df86e1799a469325c9ae3b1
Author: Jiri Pirko <jiri@xxxxxxxxxx>
Date: Thu Aug 25 10:19:40 2022 +0200
genetlink: hold read cb_lock during iteration of genl_fam_idr in genl_bind()
[ Upstream commit 8f1948bdcf2fb50e9092c0950c3c9ac591382101 ]
In genl_bind(), currently genl_lock and write cb_lock are taken
for iteration of genl_fam_idr and processing of static values
stored in struct genl_family. Take just read cb_lock for this task
as it is sufficient to guard the idr and the struct against
concurrent genl_register/unregister_family() calls.
This will allow to run genl command processing in genl_rcv() and
mnl_socket_setsockopt(.., NETLINK_ADD_MEMBERSHIP, ..) in parallel.
Reported-by: Vikas Gupta <vikas.gupta@xxxxxxxxxxxx>
Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220825081940.1283335-1-jiri@xxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 57010927e20a..76aed0571e3a 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1362,7 +1362,7 @@ static int genl_bind(struct net *net, int group)
unsigned int id;
int ret = 0;
- genl_lock_all();
+ down_read(&cb_lock);
idr_for_each_entry(&genl_fam_idr, family, id) {
const struct genl_multicast_group *grp;
@@ -1383,7 +1383,7 @@ static int genl_bind(struct net *net, int group)
break;
}
- genl_unlock_all();
+ up_read(&cb_lock);
return ret;
}
