From f406e133bed5b0a7fae05ff0188824315eae5ba1 Mon Sep 17 00:00:00 2001 From: Herbert Xu 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 Signed-off-by: Herbert Xu Acked-by: Cong Wang Signed-off-by: David S. Miller (cherry picked from commit 92964c79b357efd980812c4de5c1fd2ec8bb5520) Orabug: 25203221 CVE: CVE-2016-9806 Signed-off-by: Dhaval Giani Reviewed-by: Jack Vogel Signed-off-by: Dhaval Giani --- 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 bf6e76643f78..0ee6712e4094 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2628,6 +2628,7 @@ 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; @@ -2697,9 +2698,11 @@ 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: -- 2.50.1