Messages in this thread | | | Date | Wed, 1 Jun 2022 10:47:15 +0800 | Subject | Re: [PATCH] xfrm: xfrm_input: fix a possible memory leak in xfrm_input() | From | Hangyu Hua <> |
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On 2022/5/31 19:35, Steffen Klassert wrote: > On Tue, May 31, 2022 at 10:12:05AM +0800, Hangyu Hua wrote: >> On 2022/5/30 18:37, Steffen Klassert wrote: >>> On Mon, May 30, 2022 at 06:20:46PM +0800, Hangyu Hua wrote: >>>> xfrm_input needs to handle skb internally. But skb is not freed When >>>> xo->flags & XFRM_GRO == 0 and decaps == 0. >>>> >>>> Fixes: 7785bba299a8 ("esp: Add a software GRO codepath") >>>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com> >>>> --- >>>> net/xfrm/xfrm_input.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c >>>> index 144238a50f3d..6f9576352f30 100644 >>>> --- a/net/xfrm/xfrm_input.c >>>> +++ b/net/xfrm/xfrm_input.c >>>> @@ -742,7 +742,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type) >>>> gro_cells_receive(&gro_cells, skb); >>>> return err; >>>> } >>>> - >>>> + kfree_skb(skb); >>>> return err; >>>> } >>> >>> Did you test this? The function behind the 'afinfo->the transport_finish()' >>> pointer handles this skb and frees it in that case. >> >> int xfrm4_transport_finish(struct sk_buff *skb, int async) >> { >> struct xfrm_offload *xo = xfrm_offload(skb); >> struct iphdr *iph = ip_hdr(skb); >> >> iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; >> >> #ifndef CONFIG_NETFILTER >> if (!async) >> return -iph->protocol; <--- [1] >> #endif >> ... >> NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, >> dev_net(skb->dev), NULL, skb, skb->dev, NULL, >> xfrm4_rcv_encap_finish); <--- [2] >> return 0; >> } >> >> int xfrm6_transport_finish(struct sk_buff *skb, int async) >> { >> struct xfrm_offload *xo = xfrm_offload(skb); >> int nhlen = skb->data - skb_network_header(skb); >> >> skb_network_header(skb)[IP6CB(skb)->nhoff] = >> XFRM_MODE_SKB_CB(skb)->protocol; >> >> #ifndef CONFIG_NETFILTER >> if (!async) >> return 1; <--- [3] >> #endif >> ... >> NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, >> dev_net(skb->dev), NULL, skb, skb->dev, NULL, >> xfrm6_transport_finish2); >> return 0; <--- [4] >> } >> >> If transport_finish() return in [1] or [3], there will be a memory leak. > > No, even in that case there is no memleak. Look for instance at the > IPv4 case, we return -iph->protocol here. > Then look at ip_protocol_deliver_rcu(). If the ipprot->handler (xfrm) > returns a negative value, this is interpreted as the protocol number > and the packet is resubmitted to the next protocol handler. > > Please test your patches before you submit them in the future. Thanks for your explanation. I will be more careful in the future.
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