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UPSTREAM: netlink: Fix dump skb leak/double free

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(cherry picked from commit 92964c79b3)

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: 16b304f340 ("netlink: Eliminate kmalloc in netlink dump operation.")
Reported-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Change-Id: Ie2db6a32a49686c6d22c4a88c251b288343c7813
Bug: 33393474
This commit is contained in:
Herbert Xu
2016-05-16 17:28:16 +08:00
committed by Lorenzo Colitti
parent 1475f79c87
commit 56ea977b0f
1 changed files with 5 additions and 2 deletions
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7
net/netlink/af_netlink.c
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@@ -2784,6 +2784,7 @@ 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;
@@ -2863,9 +2864,11 @@ 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: