On Wed, Jan 6, 2016 at 10:59 PM, Cong Wang <xiyou.wangc...@gmail.com> wrote: > On Wed, Jan 6, 2016 at 11:15 AM, Konstantin Khlebnikov <koc...@gmail.com> > wrote: >> Looks like this happens because ip_options_fragment() relies on >> correct ip options length in ip control block in skb. But in >> ip_finish_output_gso() control block in segments is reused by >> skb_gso_segment(). following ip_fragment() sees some garbage. >> >> In my case there was no ip options but length becomes non-zero and >> ip_options_fragment() picked some bytes from payload and decides to >> fill huge range with IPOPT_NOOP (1). One of that ones flipped nr_frags >> in skb_shared_info at the end of data =) >> > > Hmm, it looks like SKB_GSO_CB should be cleared after skb_gso_segment() > since all the gso information should be saved in shared_info after it > finishes. > > Does a memset(0) on SKB_GSO_CB after skb_gso_segment() work as well?
This will break present logic around ip_options_fragment() - it clears options from second and following fragments. With zeroed cb it will do nothing. ip_options_fragment() can get required information directly from ip header but it also resets fields in IPCB -- probably it should stay valid here and somebody else will use it later. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
