Messages in this thread | | | Date | Tue, 31 May 2022 10:12:05 +0800 | Subject | Re: [PATCH] xfrm: xfrm_input: fix a possible memory leak in xfrm_input() | From | Hangyu Hua <> |
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On 2022/5/30 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. If it return return in [2] and [4], there will not be a memory leak. It look like my patch is incorrect.
How do you think i modify the patch as follows?
gro_cells_receive(&gro_cells, skb); return err; } - + if (err != 0) + kfree_skb(skb); return err; }
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