Messages in this thread | | | Subject | Re: [PATCH] ip6mr: Fix skb_under_panic in ip6mr_cache_report() | From | YueHaibing <> | Date | Fri, 28 Jul 2023 20:00:20 +0800 |
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On 2023/7/28 18:50, Eric Dumazet wrote: > On Fri, Jul 28, 2023 at 12:01 PM 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 >> ------------[ cut here ]------------ >> > >> 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 declar as this: >> void *skb_push(struct sk_buff *skb, unsigned int len); >> skb->data -= len; >> //0xffff888f5f86a84c - 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> >> --- >> net/ipv6/ip6mr.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c >> index cc3d5ad17257..ee9c2ff8b0e4 100644 >> --- a/net/ipv6/ip6mr.c >> +++ b/net/ipv6/ip6mr.c >> @@ -1051,9 +1051,9 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, >> int ret; >> >> #ifdef CONFIG_IPV6_PIMSM_V2 >> + int nhoff = skb_network_offset(pkt); >> if (assert == MRT6MSG_WHOLEPKT || assert == MRT6MSG_WRMIFWHOLE) >> - skb = skb_realloc_headroom(pkt, -skb_network_offset(pkt) >> - +sizeof(*msg)); >> + skb = skb_realloc_headroom(pkt, -nhoff + sizeof(*msg)); >> else >> #endif >> skb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(*msg), GFP_ATOMIC); >> @@ -1073,7 +1073,8 @@ 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->data += nhoff; >> + skb->len -= nhoff; > > __skb_pull(skb, nhoff);
Thanks, will do this in v2. > >> >> skb_push(skb, sizeof(*msg)); >> skb_reset_transport_header(skb); >> -- >> 2.34.1 >> > . >
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