netdev - [PATCH] netlink: fix state reallocation in policy export

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Message-Id: <20200819122255.6b32aa54d205.I316de8a67c79a393ae1826a1b2dcc08f31b1856e@changeid>
Date:   Wed, 19 Aug 2020 12:22:55 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     netdev@...r.kernel.org
Cc:     Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH] netlink: fix state reallocation in policy export

From: Johannes Berg <johannes.berg@...el.com>

Evidently, when I did this previously, we didn't have more than
10 policies and didn't run into the reallocation path, because
it's missing a memset() for the unused policies. Fix that.

Fixes: d07dcf9aadd6 ("netlink: add infrastructure to expose policies to userspace")
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
 net/netlink/policy.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netlink/policy.c b/net/netlink/policy.c
index f6491853c797..3f3b421fd70c 100644
--- a/net/netlink/policy.c
+++ b/net/netlink/policy.c
@@ -51,6 +51,9 @@ static int add_policy(struct nl_policy_dump **statep,
 	if (!state)
 		return -ENOMEM;
 
+	memset(&state->policies[state->n_alloc], 0,
+	       sizeof(state->policies[0]) * (n_alloc - state->n_alloc));
+
 	state->policies[state->n_alloc].policy = policy;
 	state->policies[state->n_alloc].maxtype = maxtype;
 	state->n_alloc = n_alloc;
-- 
2.26.2