Messages in this thread | ![/](/images/icornerl.gif) | | From | Eric Dumazet <> | Date | Tue, 1 Aug 2023 09:51:29 +0200 | Subject | Re: [PATCH v3] ip6mr: Fix skb_under_panic in ip6mr_cache_report() |
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On Tue, Aug 1, 2023 at 8:45 AM Yue Haibing <yuehaibing@huawei.com> wrote: > > skbuff: skb_under_panic: text:ffffffff88771f69 len:56 put:-4 > head:ffff88805f86a800 data:ffff887f5f86a850 tail:0x88 end:0x2c0 dev:pim6reg >
> When setup a vlan device on dev pim6reg, DAD ns packet may sent on reg_vif_xmit(). > reg_vif_xmit() > ip6mr_cache_report() > skb_push(skb, -skb_network_offset(pkt));//skb_network_offset(pkt) is 4 > And skb_push declared as: > void *skb_push(struct sk_buff *skb, unsigned int len); > skb->data -= len; > //0xffff88805f86a84c - 0xfffffffc = 0xffff887f5f86a850 > skb->data is set to 0xffff887f5f86a850, which is invalid mem addr, lead to skb_push() fails. > > Fixes: 14fb64e1f449 ("[IPV6] MROUTE: Support PIM-SM (SSM).") > Signed-off-by: Yue Haibing <yuehaibing@huawei.com> > --- > v3: drop unnecessary nhoff change > v2: Use __skb_pull() and fix commit log. > --- > net/ipv6/ip6mr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c > index cc3d5ad17257..67a3b8f6e72b 100644 > --- a/net/ipv6/ip6mr.c > +++ b/net/ipv6/ip6mr.c > @@ -1073,7 +1073,7 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, > And all this only to mangle msg->im6_msgtype and > to set msg->im6_mbz to "mbz" :-) > */ > - skb_push(skb, -skb_network_offset(pkt)); > + __skb_pull(skb, skb_network_offset(pkt)); > > skb_push(skb, sizeof(*msg)); > skb_reset_transport_header(skb);
Presumably this code has never been tested :/
Reviewed-by: Eric Dumazet <edumazet@google.com>
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