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Commit 92964c79 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
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netlink: Fix dump skb leak/double free 



When we free cb->skb after a dump, we do it after releasing the
lock.  This means that a new dump could have started in the time
being and we'll end up freeing their skb instead of ours.

This patch saves the skb and module before we unlock so we free
the right memory.

Fixes: 16b304f3 ("netlink: Eliminate kmalloc in netlink dump operation.")
Reported-by: default avatarBaozeng Ding <sploving1@gmail.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Acked-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 45e093ae

net/netlink/af_netlink.c

+5 −2
Original line number Diff line number Diff line
@@ -2059,6 +2059,7 @@ static int netlink_dump(struct sock *sk) 
	struct netlink_callback *cb;

	struct sk_buff *skb = NULL;

	struct nlmsghdr *nlh;

	struct module *module;

	int len, err = -ENOBUFS;

	int alloc_min_size;

	int alloc_size;
@@ -2134,9 +2135,11 @@ static int netlink_dump(struct sock *sk) 
		cb->done(cb);



	nlk->cb_running = false;

	module = cb->module;

	skb = cb->skb;

	mutex_unlock(nlk->cb_mutex);

	module_put(cb->module);

	consume_skb(cb->skb);

	module_put(module);

	consume_skb(skb);

	return 0;



errout_skb: