Messages in this thread | | | Date | Fri, 6 Oct 2023 13:59:12 +0200 | From | Florian Westphal <> | Subject | Re: [PATCH] net: xfrm: fix return value check in ipcomp_compress |
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Florian Westphal <fw@strlen.de> wrote: > Ma Ke <make_ruc2021@163.com> wrote: > > In ipcomp_compress, to avoid an unexpected result returned by > > pskb_trim, we should check the return value of pskb_trim(). > > > > Signed-off-by: Ma Ke <make_ruc2021@163.com> > > --- > > net/xfrm/xfrm_ipcomp.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c > > index 9c0fa0e1786a..5f2e6edadf48 100644 > > --- a/net/xfrm/xfrm_ipcomp.c > > +++ b/net/xfrm/xfrm_ipcomp.c > > @@ -144,7 +144,9 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) > > memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); > > local_bh_enable(); > > > > - pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); > > + err = pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr)); > > + if (unlikely(err)) > > + goto out; > > This can't be right, this now calls local_bh_enable() twice.
Furthermore, looking at this:
1. skb went through skb_linearize_cow() before, so no paged data anymore
2. Right before there is a check to bail in case compression inflated packet size.
IOW, this pskb_trim cannot fail, it boils down to __skb_trim().
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