From 923609b109211d60bc4db614f6efa22ee08764bb 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 Orabug: 25308090 [ 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 (cherry picked from commit e39cd93be0009ae4548a737756a947d2030956ab) 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 ad2ac9e6675b..5c3b85abc09b 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2665,6 +2665,7 @@ 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; @@ -2744,9 +2745,11 @@ 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