From 57b26930c7149c9ed86ba29038523a7a23140220 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 16 May 2016 17:28:16 +0800 Subject: netlink: Fix dump skb leak/double free [ Upstream commit 92964c79b357efd980812c4de5c1fd2ec8bb5520 ] 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 Signed-off-by: Herbert Xu Acked-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- 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 fe106b50053e..15fc0938e1c4 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2630,6 +2630,7 @@ 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; @@ -2699,9 +2700,11 @@ 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: -- cgit v1.2.3