Messages in this thread | | | Date | Tue, 31 May 2022 13:35:30 +0200 | From | Steffen Klassert <> | Subject | Re: [PATCH] xfrm: xfrm_input: fix a possible memory leak in xfrm_input() |
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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.
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