On 11/5/23 7:44 PM, Mina Almasry wrote: > diff --git a/net/core/datagram.c b/net/core/datagram.c > index 176eb5834746..cdd4fb129968 100644 > --- a/net/core/datagram.c > +++ b/net/core/datagram.c > @@ -425,6 +425,9 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset, > return 0; > } > > + if (skb_frags_not_readable(skb)) > + goto short_copy; > + > /* Copy paged appendix. Hmm... why does this look so complicated? */ > for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { > int end; > @@ -616,6 +619,9 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk, > { > int frag; > > + if (skb_frags_not_readable(skb)) > + return -EFAULT; This check .... > + > if (msg && msg->msg_ubuf && msg->sg_from_iter) > return msg->sg_from_iter(sk, skb, from, length); ... should go here. That allows custome sg_from_iter to have access to the skb. What matters is not expecting struct page (e.g., refcounting); if the custom iter does not do that then all is well. io_uring's iter does not look at the pages, so all good. > > diff --git a/net/core/gro.c b/net/core/gro.c > index 42d7f6755f32..56046d65386a 100644 > --- a/net/core/gro.c > +++ b/net/core/gro.c > @@ -390,6 +390,9 @@ static void gro_pull_from_frag0(struct sk_buff *skb, int grow) > { > struct skb_shared_info *pinfo = skb_shinfo(skb); > > + if (WARN_ON_ONCE(skb_frags_not_readable(skb))) > + return; > + > BUG_ON(skb->end - skb->tail < grow); > > memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow); > @@ -411,7 +414,7 @@ static void gro_try_pull_from_frag0(struct sk_buff *skb) > { > int grow = skb_gro_offset(skb) - skb_headlen(skb); > > - if (grow > 0) > + if (grow > 0 && !skb_frags_not_readable(skb)) > gro_pull_from_frag0(skb, grow); > } > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 13eca4fd25e1..f01673ed2eff 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -1230,6 +1230,14 @@ void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt) > struct page *p; > u8 *vaddr; > > + if (skb_frag_is_page_pool_iov(frag)) { Why skb_frag_is_page_pool_iov here vs skb_frags_not_readable?