Messages in this thread | | | Date | Mon, 29 Apr 2024 09:28:07 -0400 | From | Willem de Bruijn <> | Subject | Re: [PATCH net] net: prevent pulling SKB_GSO_FRAGLIST skb |
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shiming.cheng@ wrote: > From: Shiming Cheng <shiming.cheng@mediatek.com> > > BPF or TC callers may pull in a length longer than skb_headlen() > for a SKB_GSO_FRAGLIST skb. The data in fraglist will be pulled > into the linear space. However it destroys the skb's structure > and may result in an invalid segmentation or kernel exception. > > So we should add protection to stop the operation and return > error to remind callers. > > Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") > Signed-off-by: Shiming Cheng <shiming.cheng@mediatek.com> > Signed-off-by: Lena Wang <lena.wang@mediatek.com> > > --- > net/core/skbuff.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index f68f2679b086..2d35e009e814 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -6100,6 +6100,12 @@ EXPORT_SYMBOL(skb_vlan_untag); > > int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len) > { > + if (skb_is_gso(skb) && > + (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) && > + write_len > skb_headlen(skb)) { > + return -ENOMEM; > + } > +
Most callers of skb_ensure_writable pull less than headlen. It might be good to start with the write_len check. Before looking at gso type.
> if (!pskb_may_pull(skb, write_len)) > return -ENOMEM; > > -- > 2.18.0 >
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