Hi Stefan, On 05/07/18 13:16, Stefan Schmidt wrote: > Hello. > > [CC David Palma and Rabi Narayan Sahoo] > > On 02.07.2018 22:32, Alexander Aring wrote: >> This patch fixes patch add handling to take care tail and headroom for >> single 6lowpan frames. We need to be sure we have a skb with the right >> head and tailroom for single frames. This patch do it by using >> skb_copy_expand() if head and tailroom is not enough allocated by upper >> layer. >> >> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=195059 >> Reported-by: David Palma <david.palma@xxxxxxx> >> Reported-by: Rabi Narayan Sahoo <rabinarayans0828@xxxxxxxxx> >> Signed-off-by: Alexander Aring <aring@xxxxxxxxxxxx> > > David, Rabi and you please test these two patches and verify that it > fixes the problems you have? > > regards > Stefan Schmidt > The patches fix the problems! I've tested them against different packet sizes and no kernel panic. The patches were applied in Debian's 4.9.88-1+deb9u1 x86_64 kernel, which before the patches showed the reported issue. Thanks again to Alex for looking into it. Cheers, -- David >> --- >> net/ieee802154/6lowpan/tx.c | 21 ++++++++++++++++++--- >> 1 file changed, 18 insertions(+), 3 deletions(-) >> >> diff --git a/net/ieee802154/6lowpan/tx.c b/net/ieee802154/6lowpan/tx.c >> index e6ff5128e61a..d0c4d220de08 100644 >> --- a/net/ieee802154/6lowpan/tx.c >> +++ b/net/ieee802154/6lowpan/tx.c >> @@ -265,9 +265,24 @@ netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev) >> /* We must take a copy of the skb before we modify/replace the ipv6 >> * header as the header could be used elsewhere >> */ >> - skb = skb_unshare(skb, GFP_ATOMIC); >> - if (!skb) >> - return NET_XMIT_DROP; >> + if (unlikely(skb_headroom(skb) < ldev->needed_headroom || >> + skb_tailroom(skb) < ldev->needed_tailroom)) { >> + struct sk_buff *nskb; >> + >> + nskb = skb_copy_expand(skb, ldev->needed_headroom, >> + ldev->needed_tailroom, GFP_ATOMIC); >> + if (likely(skb)) { >> + consume_skb(skb); >> + skb = nskb; >> + } else { >> + kfree_skb(skb); >> + return NET_XMIT_DROP; >> + } >> + } else { >> + skb = skb_unshare(skb, GFP_ATOMIC); >> + if (!skb) >> + return NET_XMIT_DROP; >> + } >> >> ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset); >> if (ret < 0) { >>
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