| Message ID | 44e8dcf8-bf64-0407-65bb-122d0853c672@huawei.com |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v3,net] ipv6: Fix dangling pointer when ipv6 fragment | expand |
Hi hujunwei,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on net/master]
url: https://github.com/0day-ci/linux/commits/hujunwei/ipv6-Fix-dangling-pointer-when-ipv6-fragment/20190402-175602
config: i386-randconfig-x005-201913 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
net//ipv6/ip6_output.c: In function 'ip6_fragment':
>> net//ipv6/ip6_output.c:609:27: warning: 'prevhdr' is used uninitialized in this function [-Wuninitialized]
nexthdr_offset = prevhdr - skb_network_header(skb);
~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
vim +/prevhdr +609 net//ipv6/ip6_output.c
594
595 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
596 int (*output)(struct net *, struct sock *, struct sk_buff *))
597 {
598 struct sk_buff *frag;
599 struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
600 struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
601 inet6_sk(skb->sk) : NULL;
602 struct ipv6hdr *tmp_hdr;
603 struct frag_hdr *fh;
604 unsigned int mtu, hlen, left, len, nexthdr_offset;
605 int hroom, troom;
606 __be32 frag_id;
607 int ptr, offset = 0, err = 0;
608 u8 *prevhdr, nexthdr = 0;
> 609 nexthdr_offset = prevhdr - skb_network_header(skb);
610
611 err = ip6_find_1stfragopt(skb, &prevhdr);
612 if (err < 0)
613 goto fail;
614 hlen = err;
615 nexthdr = *prevhdr;
616
617 mtu = ip6_skb_dst_mtu(skb);
618
619 /* We must not fragment if the socket is set to force MTU discovery
620 * or if the skb it not generated by a local socket.
621 */
622 if (unlikely(!skb->ignore_df && skb->len > mtu))
623 goto fail_toobig;
624
625 if (IP6CB(skb)->frag_max_size) {
626 if (IP6CB(skb)->frag_max_size > mtu)
627 goto fail_toobig;
628
629 /* don't send fragments larger than what we received */
630 mtu = IP6CB(skb)->frag_max_size;
631 if (mtu < IPV6_MIN_MTU)
632 mtu = IPV6_MIN_MTU;
633 }
634
635 if (np && np->frag_size < mtu) {
636 if (np->frag_size)
637 mtu = np->frag_size;
638 }
639 if (mtu < hlen + sizeof(struct frag_hdr) + 8)
640 goto fail_toobig;
641 mtu -= hlen + sizeof(struct frag_hdr);
642
643 frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
644 &ipv6_hdr(skb)->saddr);
645
646 if (skb->ip_summed == CHECKSUM_PARTIAL &&
647 (err = skb_checksum_help(skb)))
648 goto fail;
649
650 prevhdr = skb_network_header(skb) + nexthdr_offset;
651 hroom = LL_RESERVED_SPACE(rt->dst.dev);
652 if (skb_has_frag_list(skb)) {
653 unsigned int first_len = skb_pagelen(skb);
654 struct sk_buff *frag2;
655
656 if (first_len - hlen > mtu ||
657 ((first_len - hlen) & 7) ||
658 skb_cloned(skb) ||
659 skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
660 goto slow_path;
661
662 skb_walk_frags(skb, frag) {
663 /* Correct geometry. */
664 if (frag->len > mtu ||
665 ((frag->len & 7) && frag->next) ||
666 skb_headroom(frag) < (hlen + hroom + sizeof(struct frag_hdr)))
667 goto slow_path_clean;
668
669 /* Partially cloned skb? */
670 if (skb_shared(frag))
671 goto slow_path_clean;
672
673 BUG_ON(frag->sk);
674 if (skb->sk) {
675 frag->sk = skb->sk;
676 frag->destructor = sock_wfree;
677 }
678 skb->truesize -= frag->truesize;
679 }
680
681 err = 0;
682 offset = 0;
683 /* BUILD HEADER */
684
685 *prevhdr = NEXTHDR_FRAGMENT;
686 tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
687 if (!tmp_hdr) {
688 err = -ENOMEM;
689 goto fail;
690 }
691 frag = skb_shinfo(skb)->frag_list;
692 skb_frag_list_init(skb);
693
694 __skb_pull(skb, hlen);
695 fh = __skb_push(skb, sizeof(struct frag_hdr));
696 __skb_push(skb, hlen);
697 skb_reset_network_header(skb);
698 memcpy(skb_network_header(skb), tmp_hdr, hlen);
699
700 fh->nexthdr = nexthdr;
701 fh->reserved = 0;
702 fh->frag_off = htons(IP6_MF);
703 fh->identification = frag_id;
704
705 first_len = skb_pagelen(skb);
706 skb->data_len = first_len - skb_headlen(skb);
707 skb->len = first_len;
708 ipv6_hdr(skb)->payload_len = htons(first_len -
709 sizeof(struct ipv6hdr));
710
711 for (;;) {
712 /* Prepare header of the next frame,
713 * before previous one went down. */
714 if (frag) {
715 frag->ip_summed = CHECKSUM_NONE;
716 skb_reset_transport_header(frag);
717 fh = __skb_push(frag, sizeof(struct frag_hdr));
718 __skb_push(frag, hlen);
719 skb_reset_network_header(frag);
720 memcpy(skb_network_header(frag), tmp_hdr,
721 hlen);
722 offset += skb->len - hlen - sizeof(struct frag_hdr);
723 fh->nexthdr = nexthdr;
724 fh->reserved = 0;
725 fh->frag_off = htons(offset);
726 if (frag->next)
727 fh->frag_off |= htons(IP6_MF);
728 fh->identification = frag_id;
729 ipv6_hdr(frag)->payload_len =
730 htons(frag->len -
731 sizeof(struct ipv6hdr));
732 ip6_copy_metadata(frag, skb);
733 }
734
735 err = output(net, sk, skb);
736 if (!err)
737 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
738 IPSTATS_MIB_FRAGCREATES);
739
740 if (err || !frag)
741 break;
742
743 skb = frag;
744 frag = skb->next;
745 skb_mark_not_on_list(skb);
746 }
747
748 kfree(tmp_hdr);
749
750 if (err == 0) {
751 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
752 IPSTATS_MIB_FRAGOKS);
753 return 0;
754 }
755
756 kfree_skb_list(frag);
757
758 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
759 IPSTATS_MIB_FRAGFAILS);
760 return err;
761
762 slow_path_clean:
763 skb_walk_frags(skb, frag2) {
764 if (frag2 == frag)
765 break;
766 frag2->sk = NULL;
767 frag2->destructor = NULL;
768 skb->truesize += frag2->truesize;
769 }
770 }
771
772 slow_path:
773 left = skb->len - hlen; /* Space per frame */
774 ptr = hlen; /* Where to start from */
775
776 /*
777 * Fragment the datagram.
778 */
779
780 troom = rt->dst.dev->needed_tailroom;
781
782 /*
783 * Keep copying data until we run out.
784 */
785 while (left > 0) {
786 u8 *fragnexthdr_offset;
787
788 len = left;
789 /* IF: it doesn't fit, use 'mtu' - the data space left */
790 if (len > mtu)
791 len = mtu;
792 /* IF: we are not sending up to and including the packet end
793 then align the next start on an eight byte boundary */
794 if (len < left) {
795 len &= ~7;
796 }
797
798 /* Allocate buffer */
799 frag = alloc_skb(len + hlen + sizeof(struct frag_hdr) +
800 hroom + troom, GFP_ATOMIC);
801 if (!frag) {
802 err = -ENOMEM;
803 goto fail;
804 }
805
806 /*
807 * Set up data on packet
808 */
809
810 ip6_copy_metadata(frag, skb);
811 skb_reserve(frag, hroom);
812 skb_put(frag, len + hlen + sizeof(struct frag_hdr));
813 skb_reset_network_header(frag);
814 fh = (struct frag_hdr *)(skb_network_header(frag) + hlen);
815 frag->transport_header = (frag->network_header + hlen +
816 sizeof(struct frag_hdr));
817
818 /*
819 * Charge the memory for the fragment to any owner
820 * it might possess
821 */
822 if (skb->sk)
823 skb_set_owner_w(frag, skb->sk);
824
825 /*
826 * Copy the packet header into the new buffer.
827 */
828 skb_copy_from_linear_data(skb, skb_network_header(frag), hlen);
829
830 fragnexthdr_offset = skb_network_header(frag);
831 fragnexthdr_offset += prevhdr - skb_network_header(skb);
832 *fragnexthdr_offset = NEXTHDR_FRAGMENT;
833
834 /*
835 * Build fragment header.
836 */
837 fh->nexthdr = nexthdr;
838 fh->reserved = 0;
839 fh->identification = frag_id;
840
841 /*
842 * Copy a block of the IP datagram.
843 */
844 BUG_ON(skb_copy_bits(skb, ptr, skb_transport_header(frag),
845 len));
846 left -= len;
847
848 fh->frag_off = htons(offset);
849 if (left > 0)
850 fh->frag_off |= htons(IP6_MF);
851 ipv6_hdr(frag)->payload_len = htons(frag->len -
852 sizeof(struct ipv6hdr));
853
854 ptr += len;
855 offset += len;
856
857 /*
858 * Put this fragment into the sending queue.
859 */
860 err = output(net, sk, frag);
861 if (err)
862 goto fail;
863
864 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
865 IPSTATS_MIB_FRAGCREATES);
866 }
867 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
868 IPSTATS_MIB_FRAGOKS);
869 consume_skb(skb);
870 return err;
871
872 fail_toobig:
873 if (skb->sk && dst_allfrag(skb_dst(skb)))
874 sk_nocaps_add(skb->sk, NETIF_F_GSO_MASK);
875
876 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
877 err = -EMSGSIZE;
878
879 fail:
880 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
881 IPSTATS_MIB_FRAGFAILS);
882 kfree_skb(skb);
883 return err;
884 }
885
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On Tue, Apr 02, 2019 at 06:49:03PM +0800, kbuild test robot wrote: > Hi hujunwei, > > Thank you for the patch! Perhaps something to improve: > > [auto build test WARNING on net/master] > > url: https://github.com/0day-ci/linux/commits/hujunwei/ipv6-Fix-dangling-pointer-when-ipv6-fragment/20190402-175602 > config: i386-randconfig-x005-201913 (attached as .config) > compiler: gcc-7 (Debian 7.3.0-1) 7.3.0 > reproduce: > # save the attached .config to linux build tree > make ARCH=i386 > > All warnings (new ones prefixed by >>): > > net//ipv6/ip6_output.c: In function 'ip6_fragment': > >> net//ipv6/ip6_output.c:609:27: warning: 'prevhdr' is used uninitialized in this function [-Wuninitialized] > nexthdr_offset = prevhdr - skb_network_header(skb); > ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~ > > vim +/prevhdr +609 net//ipv6/ip6_output.c > > 594 > 595 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, > 596 int (*output)(struct net *, struct sock *, struct sk_buff *)) > 597 { > 598 struct sk_buff *frag; > 599 struct rt6_info *rt = (struct rt6_info *)skb_dst(skb); > 600 struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ? > 601 inet6_sk(skb->sk) : NULL; > 602 struct ipv6hdr *tmp_hdr; > 603 struct frag_hdr *fh; > 604 unsigned int mtu, hlen, left, len, nexthdr_offset; > 605 int hroom, troom; > 606 __be32 frag_id; > 607 int ptr, offset = 0, err = 0; > 608 u8 *prevhdr, nexthdr = 0; > > 609 nexthdr_offset = prevhdr - skb_network_header(skb); hmm... This line has been moved up since v2. :( > 610 > 611 err = ip6_find_1stfragopt(skb, &prevhdr); > 612 if (err < 0) > 613 goto fail; > 614 hlen = err; > 615 nexthdr = *prevhdr; > 616 > 617 mtu = ip6_skb_dst_mtu(skb); > 618 > 619 /* We must not fragment if the socket is set to force MTU discovery > 620 * or if the skb it not generated by a local socket. > 621 */ > 622 if (unlikely(!skb->ignore_df && skb->len > mtu)) > 623 goto fail_toobig; > 624 > 625 if (IP6CB(skb)->frag_max_size) { > 626 if (IP6CB(skb)->frag_max_size > mtu) > 627 goto fail_toobig; > 628 > 629 /* don't send fragments larger than what we received */ > 630 mtu = IP6CB(skb)->frag_max_size; > 631 if (mtu < IPV6_MIN_MTU) > 632 mtu = IPV6_MIN_MTU; > 633 } > 634 > 635 if (np && np->frag_size < mtu) { > 636 if (np->frag_size) > 637 mtu = np->frag_size; > 638 } > 639 if (mtu < hlen + sizeof(struct frag_hdr) + 8) > 640 goto fail_toobig; > 641 mtu -= hlen + sizeof(struct frag_hdr); > 642 > 643 frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, > 644 &ipv6_hdr(skb)->saddr); > 645 > 646 if (skb->ip_summed == CHECKSUM_PARTIAL && > 647 (err = skb_checksum_help(skb))) > 648 goto fail; > 649 > 650 prevhdr = skb_network_header(skb) + nexthdr_offset; > 651 hroom = LL_RESERVED_SPACE(rt->dst.dev); > 652 if (skb_has_frag_list(skb)) { > 653 unsigned int first_len = skb_pagelen(skb); > 654 struct sk_buff *frag2; > 655 > 656 if (first_len - hlen > mtu || > 657 ((first_len - hlen) & 7) || > 658 skb_cloned(skb) || > 659 skb_headroom(skb) < (hroom + sizeof(struct frag_hdr))) > 660 goto slow_path; > 661 > 662 skb_walk_frags(skb, frag) { > 663 /* Correct geometry. */ > 664 if (frag->len > mtu || > 665 ((frag->len & 7) && frag->next) || > 666 skb_headroom(frag) < (hlen + hroom + sizeof(struct frag_hdr))) > 667 goto slow_path_clean; > 668 > 669 /* Partially cloned skb? */ > 670 if (skb_shared(frag)) > 671 goto slow_path_clean; > 672 > 673 BUG_ON(frag->sk); > 674 if (skb->sk) { > 675 frag->sk = skb->sk; > 676 frag->destructor = sock_wfree; > 677 } > 678 skb->truesize -= frag->truesize; > 679 } > 680 > 681 err = 0; > 682 offset = 0; > 683 /* BUILD HEADER */ > 684 > 685 *prevhdr = NEXTHDR_FRAGMENT; > 686 tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC); > 687 if (!tmp_hdr) { > 688 err = -ENOMEM; > 689 goto fail; > 690 } > 691 frag = skb_shinfo(skb)->frag_list; > 692 skb_frag_list_init(skb); > 693 > 694 __skb_pull(skb, hlen); > 695 fh = __skb_push(skb, sizeof(struct frag_hdr)); > 696 __skb_push(skb, hlen); > 697 skb_reset_network_header(skb); > 698 memcpy(skb_network_header(skb), tmp_hdr, hlen); > 699 > 700 fh->nexthdr = nexthdr; > 701 fh->reserved = 0; > 702 fh->frag_off = htons(IP6_MF); > 703 fh->identification = frag_id; > 704 > 705 first_len = skb_pagelen(skb); > 706 skb->data_len = first_len - skb_headlen(skb); > 707 skb->len = first_len; > 708 ipv6_hdr(skb)->payload_len = htons(first_len - > 709 sizeof(struct ipv6hdr)); > 710 > 711 for (;;) { > 712 /* Prepare header of the next frame, > 713 * before previous one went down. */ > 714 if (frag) { > 715 frag->ip_summed = CHECKSUM_NONE; > 716 skb_reset_transport_header(frag); > 717 fh = __skb_push(frag, sizeof(struct frag_hdr)); > 718 __skb_push(frag, hlen); > 719 skb_reset_network_header(frag); > 720 memcpy(skb_network_header(frag), tmp_hdr, > 721 hlen); > 722 offset += skb->len - hlen - sizeof(struct frag_hdr); > 723 fh->nexthdr = nexthdr; > 724 fh->reserved = 0; > 725 fh->frag_off = htons(offset); > 726 if (frag->next) > 727 fh->frag_off |= htons(IP6_MF); > 728 fh->identification = frag_id; > 729 ipv6_hdr(frag)->payload_len = > 730 htons(frag->len - > 731 sizeof(struct ipv6hdr)); > 732 ip6_copy_metadata(frag, skb); > 733 } > 734 > 735 err = output(net, sk, skb); > 736 if (!err) > 737 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst), > 738 IPSTATS_MIB_FRAGCREATES); > 739 > 740 if (err || !frag) > 741 break; > 742 > 743 skb = frag; > 744 frag = skb->next; > 745 skb_mark_not_on_list(skb); > 746 } > 747 > 748 kfree(tmp_hdr); > 749 > 750 if (err == 0) { > 751 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst), > 752 IPSTATS_MIB_FRAGOKS); > 753 return 0; > 754 } > 755 > 756 kfree_skb_list(frag); > 757 > 758 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst), > 759 IPSTATS_MIB_FRAGFAILS); > 760 return err; > 761 > 762 slow_path_clean: > 763 skb_walk_frags(skb, frag2) { > 764 if (frag2 == frag) > 765 break; > 766 frag2->sk = NULL; > 767 frag2->destructor = NULL; > 768 skb->truesize += frag2->truesize; > 769 } > 770 } > 771 > 772 slow_path: > 773 left = skb->len - hlen; /* Space per frame */ > 774 ptr = hlen; /* Where to start from */ > 775 > 776 /* > 777 * Fragment the datagram. > 778 */ > 779 > 780 troom = rt->dst.dev->needed_tailroom; > 781 > 782 /* > 783 * Keep copying data until we run out. > 784 */ > 785 while (left > 0) { > 786 u8 *fragnexthdr_offset; > 787 > 788 len = left; > 789 /* IF: it doesn't fit, use 'mtu' - the data space left */ > 790 if (len > mtu) > 791 len = mtu; > 792 /* IF: we are not sending up to and including the packet end > 793 then align the next start on an eight byte boundary */ > 794 if (len < left) { > 795 len &= ~7; > 796 } > 797 > 798 /* Allocate buffer */ > 799 frag = alloc_skb(len + hlen + sizeof(struct frag_hdr) + > 800 hroom + troom, GFP_ATOMIC); > 801 if (!frag) { > 802 err = -ENOMEM; > 803 goto fail; > 804 } > 805 > 806 /* > 807 * Set up data on packet > 808 */ > 809 > 810 ip6_copy_metadata(frag, skb); > 811 skb_reserve(frag, hroom); > 812 skb_put(frag, len + hlen + sizeof(struct frag_hdr)); > 813 skb_reset_network_header(frag); > 814 fh = (struct frag_hdr *)(skb_network_header(frag) + hlen); > 815 frag->transport_header = (frag->network_header + hlen + > 816 sizeof(struct frag_hdr)); > 817 > 818 /* > 819 * Charge the memory for the fragment to any owner > 820 * it might possess > 821 */ > 822 if (skb->sk) > 823 skb_set_owner_w(frag, skb->sk); > 824 > 825 /* > 826 * Copy the packet header into the new buffer. > 827 */ > 828 skb_copy_from_linear_data(skb, skb_network_header(frag), hlen); > 829 > 830 fragnexthdr_offset = skb_network_header(frag); > 831 fragnexthdr_offset += prevhdr - skb_network_header(skb); > 832 *fragnexthdr_offset = NEXTHDR_FRAGMENT; > 833 > 834 /* > 835 * Build fragment header. > 836 */ > 837 fh->nexthdr = nexthdr; > 838 fh->reserved = 0; > 839 fh->identification = frag_id; > 840 > 841 /* > 842 * Copy a block of the IP datagram. > 843 */ > 844 BUG_ON(skb_copy_bits(skb, ptr, skb_transport_header(frag), > 845 len)); > 846 left -= len; > 847 > 848 fh->frag_off = htons(offset); > 849 if (left > 0) > 850 fh->frag_off |= htons(IP6_MF); > 851 ipv6_hdr(frag)->payload_len = htons(frag->len - > 852 sizeof(struct ipv6hdr)); > 853 > 854 ptr += len; > 855 offset += len; > 856 > 857 /* > 858 * Put this fragment into the sending queue. > 859 */ > 860 err = output(net, sk, frag); > 861 if (err) > 862 goto fail; > 863 > 864 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), > 865 IPSTATS_MIB_FRAGCREATES); > 866 } > 867 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), > 868 IPSTATS_MIB_FRAGOKS); > 869 consume_skb(skb); > 870 return err; > 871 > 872 fail_toobig: > 873 if (skb->sk && dst_allfrag(skb_dst(skb))) > 874 sk_nocaps_add(skb->sk, NETIF_F_GSO_MASK); > 875 > 876 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); > 877 err = -EMSGSIZE; > 878 > 879 fail: > 880 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), > 881 IPSTATS_MIB_FRAGFAILS); > 882 kfree_skb(skb); > 883 return err; > 884 } > 885 > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://urldefense.proofpoint.com/v2/url?u=https-3A__lists.01.org_pipermail_kbuild-2Dall&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=VQnoQ7LvghIj0gVEaiQSUw&m=VM2d9MD3GON8eQRY0bYRU7OGyFCoSiaFiYJJa6-3rDU&s=p3p0GnDqN_d4cCUIgH993sIXi_Sw8tUInnni3uMPXKk&e= Intel Corporation
On 2019/4/2 23:34, Martin Lau wrote: > On Tue, Apr 02, 2019 at 06:49:03PM +0800, kbuild test robot wrote: >> Hi hujunwei, >> >> Thank you for the patch! Perhaps something to improve: >> >> [auto build test WARNING on net/master] >> >> >> vim +/prevhdr +609 net//ipv6/ip6_output.c >> >> 594 >> 595 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, >> 596 int (*output)(struct net *, struct sock *, struct sk_buff *)) >> 597 { >> 598 struct sk_buff *frag; >> 599 struct rt6_info *rt = (struct rt6_info *)skb_dst(skb); >> 600 struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ? >> 601 inet6_sk(skb->sk) : NULL; >> 602 struct ipv6hdr *tmp_hdr; >> 603 struct frag_hdr *fh; >> 604 unsigned int mtu, hlen, left, len, nexthdr_offset; >> 605 int hroom, troom; >> 606 __be32 frag_id; >> 607 int ptr, offset = 0, err = 0; >> 608 u8 *prevhdr, nexthdr = 0; >> > 609 nexthdr_offset = prevhdr - skb_network_header(skb); > hmm... This line has been moved up since v2. :( Hi Martin, Thank you for your remind, I sorry for this, i send the patch v4 yesterday.
Hi hujunwei,
url: https://github.com/0day-ci/linux/commits/hujunwei/ipv6-Fix-dangling-pointer-when-ipv6-fragment/20190402-175602
New smatch warnings:
net/ipv6/ip6_output.c:609 ip6_fragment() error: uninitialized symbol 'prevhdr'.
Old smatch warnings:
net/ipv6/ip6_output.c:247 ip6_xmit() error: we previously assumed 'np' could be null (see line 241)
# https://github.com/0day-ci/linux/commit/7f25fe5b3011737e52e4d8b4a2dfcafd46677115
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 7f25fe5b3011737e52e4d8b4a2dfcafd46677115
vim +/prevhdr +609 net/ipv6/ip6_output.c
^1da177e4 Linus Torvalds 2005-04-16 594
7d8c6e391 Eric W. Biederman 2015-06-12 595 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
7d8c6e391 Eric W. Biederman 2015-06-12 596 int (*output)(struct net *, struct sock *, struct sk_buff *))
^1da177e4 Linus Torvalds 2005-04-16 597 {
^1da177e4 Linus Torvalds 2005-04-16 598 struct sk_buff *frag;
adf30907d Eric Dumazet 2009-06-02 599 struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
f60e5990d hannes@stressinduktion.org 2015-04-01 600 struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
f60e5990d hannes@stressinduktion.org 2015-04-01 601 inet6_sk(skb->sk) : NULL;
^1da177e4 Linus Torvalds 2005-04-16 602 struct ipv6hdr *tmp_hdr;
^1da177e4 Linus Torvalds 2005-04-16 603 struct frag_hdr *fh;
7f25fe5b3 Junwei Hu 2019-04-02 604 unsigned int mtu, hlen, left, len, nexthdr_offset;
a7ae19922 Herbert Xu 2011-11-18 605 int hroom, troom;
286c2349f Martin KaFai Lau 2015-05-22 606 __be32 frag_id;
^1da177e4 Linus Torvalds 2005-04-16 607 int ptr, offset = 0, err = 0;
^1da177e4 Linus Torvalds 2005-04-16 608 u8 *prevhdr, nexthdr = 0;
^^^^^^^^
7f25fe5b3 Junwei Hu 2019-04-02 @609 nexthdr_offset = prevhdr - skb_network_header(skb);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^1da177e4 Linus Torvalds 2005-04-16 610
7dd7eb951 David S. Miller 2017-05-17 611 err = ip6_find_1stfragopt(skb, &prevhdr);
^^^^^^^^
7dd7eb951 David S. Miller 2017-05-17 612 if (err < 0)
2423496af Craig Gallek 2017-05-16 613 goto fail;
7dd7eb951 David S. Miller 2017-05-17 614 hlen = err;
^1da177e4 Linus Torvalds 2005-04-16 615 nexthdr = *prevhdr;
^1da177e4 Linus Torvalds 2005-04-16 616
628a5c561 John Heffner 2007-04-20 617 mtu = ip6_skb_dst_mtu(skb);
b881ef760 John Heffner 2007-04-20 618
b881ef760 John Heffner 2007-04-20 619 /* We must not fragment if the socket is set to force MTU discovery
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On 2019/4/3 13:01, Dan Carpenter wrote: > Hi hujunwei, > > url: https://github.com/0day-ci/linux/commits/hujunwei/ipv6-Fix-dangling-pointer-when-ipv6-fragment/20190402-175602 > > New smatch warnings: > net/ipv6/ip6_output.c:609 ip6_fragment() error: uninitialized symbol 'prevhdr'. > > Old smatch warnings: > net/ipv6/ip6_output.c:247 ip6_xmit() error: we previously assumed 'np' could be null (see line 241) > > # https://github.com/0day-ci/linux/commit/7f25fe5b3011737e52e4d8b4a2dfcafd46677115 > git remote add linux-review https://github.com/0day-ci/linux > git remote update linux-review > git checkout 7f25fe5b3011737e52e4d8b4a2dfcafd46677115 > vim +/prevhdr +609 net/ipv6/ip6_output.c > > ^1da177e4 Linus Torvalds 2005-04-16 594 > 7d8c6e391 Eric W. Biederman 2015-06-12 595 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, > 7d8c6e391 Eric W. Biederman 2015-06-12 596 int (*output)(struct net *, struct sock *, struct sk_buff *)) > ^1da177e4 Linus Torvalds 2005-04-16 597 { > ^1da177e4 Linus Torvalds 2005-04-16 598 struct sk_buff *frag; > adf30907d Eric Dumazet 2009-06-02 599 struct rt6_info *rt = (struct rt6_info *)skb_dst(skb); > f60e5990d hannes@stressinduktion.org 2015-04-01 600 struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ? > f60e5990d hannes@stressinduktion.org 2015-04-01 601 inet6_sk(skb->sk) : NULL; > ^1da177e4 Linus Torvalds 2005-04-16 602 struct ipv6hdr *tmp_hdr; > ^1da177e4 Linus Torvalds 2005-04-16 603 struct frag_hdr *fh; > 7f25fe5b3 Junwei Hu 2019-04-02 604 unsigned int mtu, hlen, left, len, nexthdr_offset; > a7ae19922 Herbert Xu 2011-11-18 605 int hroom, troom; > 286c2349f Martin KaFai Lau 2015-05-22 606 __be32 frag_id; > ^1da177e4 Linus Torvalds 2005-04-16 607 int ptr, offset = 0, err = 0; > ^1da177e4 Linus Torvalds 2005-04-16 608 u8 *prevhdr, nexthdr = 0; > ^^^^^^^^ > 7f25fe5b3 Junwei Hu 2019-04-02 @609 nexthdr_offset = prevhdr - skb_network_header(skb); > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation > > . > Hi Dan, Thank you for your remind, I sorry for this, i send the patch v4 yesterday. You can get it from the mail list.
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index edbd12067170..533be3268e52 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -601,11 +601,12 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, inet6_sk(skb->sk) : NULL; struct ipv6hdr *tmp_hdr; struct frag_hdr *fh; - unsigned int mtu, hlen, left, len; + unsigned int mtu, hlen, left, len, nexthdr_offset; int hroom, troom; __be32 frag_id; int ptr, offset = 0, err = 0; u8 *prevhdr, nexthdr = 0; + nexthdr_offset = prevhdr - skb_network_header(skb); err = ip6_find_1stfragopt(skb, &prevhdr); if (err < 0) @@ -646,6 +647,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, (err = skb_checksum_help(skb))) goto fail; + prevhdr = skb_network_header(skb) + nexthdr_offset; hroom = LL_RESERVED_SPACE(rt->dst.dev); if (skb_has_frag_list(skb)) { unsigned int first_len = skb_pagelen(skb);