[v3 PATCH] xfrm: ipcomp: Free destination pages on acomp errors

[Herbert Xu <herbert@gondor.apana.org.au>]

Orion Zhu <zylzyl2333@gmail.com> wrote:
>
> Thanks, but I think moving the label is not safe for all paths reaching
> ipcomp_post_acomp().

Thanks for checking!

We could fix this by checking whether req is NULL and whether
sg_page(dsg) is NULL.

---8<---
Move the out_free_req label up by a couple of lines so that the
allocated dst SG list gets freed on error as well as success.

Fixes: eb2953d26971 ("xfrm: ipcomp: Use crypto_acomp interface")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 5f38dff16177..671d48f8c937 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -51,11 +51,15 @@ static int ipcomp_post_acomp(struct sk_buff *skb, int err, int hlen)
 	struct scatterlist *dsg;
 	int len, dlen;
 
-	if (unlikely(err))
-		goto out_free_req;
+	if (unlikely(!req))
+		return err;
 
 	extra = acomp_request_extra(req);
 	dsg = extra->sg;
+
+	if (unlikely(err))
+		goto out_free_req;
+
 	dlen = req->dlen;
 
 	pskb_trim_unique(skb, 0);
@@ -84,10 +88,10 @@ static int ipcomp_post_acomp(struct sk_buff *skb, int err, int hlen)
 		skb_shinfo(skb)->nr_frags++;
 	} while ((dlen -= len));
 
-	for (; dsg; dsg = sg_next(dsg))
+out_free_req:
+	for (; dsg && sg_page(dsg); dsg = sg_next(dsg))
 		__free_page(sg_page(dsg));
 
-out_free_req:
 	acomp_request_free(req);
 	return err;
 }
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt