Messages in this thread | | | Subject | Re: [PATCH IPV6 1/1] ipv6: allocate enough headroom in ip6_finish_output2() | From | Vasily Averin <> | Date | Wed, 7 Jul 2021 20:53:08 +0300 |
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On 7/7/21 8:41 PM, Eric Dumazet wrote: > On 7/7/21 6:42 PM, Jakub Kicinski wrote: >> On Wed, 7 Jul 2021 08:45:13 -0600 David Ahern wrote: >>> On 7/7/21 8:04 AM, Vasily Averin wrote: >>>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c >>>> index ff4f9eb..e5af740 100644 >>>> --- a/net/ipv6/ip6_output.c >>>> +++ b/net/ipv6/ip6_output.c >>>> @@ -61,9 +61,24 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * >>>> struct dst_entry *dst = skb_dst(skb); >>>> struct net_device *dev = dst->dev; >>>> const struct in6_addr *nexthop; >>>> + unsigned int hh_len = LL_RESERVED_SPACE(dev); >>>> struct neighbour *neigh; >>>> int ret; >>>> >>>> + /* Be paranoid, rather than too clever. */ >>>> + if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { >>>> + struct sk_buff *skb2; >>>> + >>>> + skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); >>> >>> why not use hh_len here? >> >> Is there a reason for the new skb? Why not pskb_expand_head()? > > pskb_expand_head() might crash, if skb is shared. > > We possibly can add a helper, factorizing all this, > and eventually use pskb_expand_head() if safe.
Thank you for feedback, I'll do it in 2nd version. Vasily Averin
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