| Message ID | 20210625102354.18266-1-paskripkin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | net: xfrm: fix memory leak in xfrm_user_rcv_msg | expand |
On Fri, Jun 25, 2021 at 01:23:54PM +0300, Pavel Skripkin wrote: > Syzbot reported memory leak in xfrm_user_rcv_msg(). The > problem was is non-freed skb's frag_list. > > In skb_release_all() skb_release_data() will be called only > in case of skb->head != NULL, but netlink_skb_destructor() > sets head to NULL. So, allocated frag_list skb should be > freed manualy, since consume_skb() won't take care of it > > Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator") > Reported-and-tested-by: syzbot+fb347cf82c73a90efcca@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Applied, thanks a lot!
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index f0aecee4d539..ff60ff804074 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -2811,6 +2811,16 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, err = link->doit(skb, nlh, attrs); + /* We need to free skb allocated in xfrm_alloc_compat() before + * returning from this function, because consume_skb() won't take + * care of frag_list since netlink destructor sets + * sbk->head to NULL. (see netlink_skb_destructor()) + */ + if (skb_has_frag_list(skb)) { + kfree_skb(skb_shinfo(skb)->frag_list); + skb_shinfo(skb)->frag_list = NULL; + } + err: kvfree(nlh64); return err;
Syzbot reported memory leak in xfrm_user_rcv_msg(). The problem was is non-freed skb's frag_list. In skb_release_all() skb_release_data() will be called only in case of skb->head != NULL, but netlink_skb_destructor() sets head to NULL. So, allocated frag_list skb should be freed manualy, since consume_skb() won't take care of it Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator") Reported-and-tested-by: syzbot+fb347cf82c73a90efcca@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- One thing I'm not sure about is did I choose the rigth place to free this skb, maybe we can move this clean up a little bit deeper, like in xfrm_alloc_userspi()? --- net/xfrm/xfrm_user.c | 10 ++++++++++ 1 file changed, 10 insertions(+)