netdev - [PATCH net] devlink: protect devlink dump by the instance lock

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Message-Id: <20221216044122.1863550-1-kuba@kernel.org>
Date:   Thu, 15 Dec 2022 20:41:22 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
        jacob.e.keller@...el.com, Jakub Kicinski <kuba@...nel.org>,
        jiri@...dia.com, moshe@...lanox.com
Subject: [PATCH net] devlink: protect devlink dump by the instance lock

Take the instance lock around devlink_nl_fill() when dumping,
doit takes it already.

We are only dumping basic info so in the worst case we were risking
data races around the reload statistics. Also note that the reloads
themselves had not been under the instance lock until recently, so
the selection of the Fixes tag is inherently questionable.

Fixes: a254c264267e ("devlink: Add reload stats")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: jiri@...dia.com
CC: moshe@...lanox.com
---
 net/core/devlink.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index d2df30829083..032d6d0a5ce6 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -1648,10 +1648,13 @@ static int devlink_nl_cmd_get_dumpit(struct sk_buff *msg,
 			continue;
 		}
 
+		devl_lock(devlink);
 		err = devlink_nl_fill(msg, devlink, DEVLINK_CMD_NEW,
 				      NETLINK_CB(cb->skb).portid,
 				      cb->nlh->nlmsg_seq, NLM_F_MULTI);
+		devl_unlock(devlink);
 		devlink_put(devlink);
+
 		if (err)
 			goto out;
 		idx++;
-- 
2.38.1