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Commit 5e96855fc505082389813afcf796d4c46301d4fe

Authored by Tony Cheneau
Committed by David S. Miller
1 parent 4576039ffc
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

6lowpan: Change byte order when storing/accessing to len field 

Lenght field should be encoded using big endian byte order, such as intend in the specs.
As it is currently written, the len field would not be decoded properly on an implementation using the correct byte ordering. Hence, it could lead to interroperability issues.

Also, I rewrote the code so that iphc0 argument of lowpan_alloc_new_frame could be removed.

Signed-off-by: Tony Cheneau <tony.cheneau@amnesiak.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Showing 1 changed file with 12 additions and 8 deletions Side-by-side Diff

net/ieee802154/6lowpan.c
Diff comments   View file @ 5e96855
... ... @@ -645,7 +645,7 @@
645 645 }
646 646  
647 647 static struct lowpan_fragment *
648   -lowpan_alloc_new_frame(struct sk_buff *skb, u8 iphc0, u8 len, u16 tag)
  648 +lowpan_alloc_new_frame(struct sk_buff *skb, u8 len, u16 tag)
649 649 {
650 650 struct lowpan_fragment *frame;
651 651  
... ... @@ -656,7 +656,7 @@
656 656  
657 657 INIT_LIST_HEAD(&frame->list);
658 658  
659   - frame->length = (iphc0 & 7) | (len << 3);
  659 + frame->length = len;
660 660 frame->tag = tag;
661 661  
662 662 /* allocate buffer for frame assembling */
663 663  
664 664  
... ... @@ -714,14 +714,18 @@
714 714 case LOWPAN_DISPATCH_FRAGN:
715 715 {
716 716 struct lowpan_fragment *frame;
717   - u8 len, offset;
718   - u16 tag;
  717 + /* slen stores the rightmost 8 bits of the 11 bits length */
  718 + u8 slen, offset;
  719 + u16 len, tag;
719 720 bool found = false;
720 721  
721   - if (lowpan_fetch_skb_u8(skb, &len) || /* frame length */
  722 + if (lowpan_fetch_skb_u8(skb, &slen) || /* frame length */
722 723 lowpan_fetch_skb_u16(skb, &tag)) /* fragment tag */
723 724 goto drop;
724 725  
  726 + /* adds the 3 MSB to the 8 LSB to retrieve the 11 bits length */
  727 + len = ((iphc0 & 7) << 8) | slen;
  728 +
725 729 /*
726 730 * check if frame assembling with the same tag is
727 731 * already in progress
... ... @@ -736,7 +740,7 @@
736 740  
737 741 /* alloc new frame structure */
738 742 if (!found) {
739   - frame = lowpan_alloc_new_frame(skb, iphc0, len, tag);
  743 + frame = lowpan_alloc_new_frame(skb, len, tag);
740 744 if (!frame)
741 745 goto unlock_and_drop;
742 746 }
... ... @@ -1004,8 +1008,8 @@
1004 1008 tag = fragment_tag++;
1005 1009  
1006 1010 /* first fragment header */
1007   - head[0] = LOWPAN_DISPATCH_FRAG1 | (payload_length & 0x7);
1008   - head[1] = (payload_length >> 3) & 0xff;
  1011 + head[0] = LOWPAN_DISPATCH_FRAG1 | ((payload_length >> 8) & 0x7);
  1012 + head[1] = payload_length & 0xff;
1009 1013 head[2] = tag >> 8;
1010 1014 head[3] = tag & 0xff;
1011 1015