From 9ecec1a92104b66f462058454d20b7bf23b18c9c Mon Sep 17 00:00:00 2001
From: Sivacharan Paka <sipaka@codeaurora.org>
Date: Mon, 16 May 2016 17:28:16 +0800
Subject: [PATCH] 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: 16b304f3404f ("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>
Git-repo:http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git
Git-commit: 92964c79b357efd980812c4de5c1fd2ec8bb5520
Change-Id: If2ea32cfd98906c8bce71dee4c086a24a58a274f
Signed-off-by: Srinivasa Rao Kuppala <srkupp@codeaurora.org>
---
net/netlink/af_netlink.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 609d49b0db5e..c5f01e21ae9e 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2448,6 +2448,7 @@ 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_size;
@@ -2497,9 +2498,11 @@ 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:
--
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