* [PATCH] ipv4: fix a potential use after free in gre_offload.c
@ 2014-10-18 9:26 roy.qing.li
2014-10-18 15:47 ` Eric Dumazet
2014-10-18 17:07 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: roy.qing.li @ 2014-10-18 9:26 UTC (permalink / raw)
To: netdev; +Cc: weichunc
From: Li RongQing <roy.qing.li@gmail.com>
pskb_may_pull() may change skb->data and make greh pointer oboslete;
so need to reassign greh;
but since first calling pskb_may_pull already ensured that skb->data
has enough space for greh, so move the reference of greh before second
calling pskb_may_pull(), to avoid reassign greh.
Fixes: 7a7ffbabf9("ipv4: fix tunneled VM traffic over hw VXLAN/GRE GSO NIC")
Cc: Wei-Chun Chao <weichunc@plumgrid.com>
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
---
net/ipv4/gre_offload.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index a777295..ccda096 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -55,13 +55,13 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
if (csum)
skb->encap_hdr_csum = 1;
- if (unlikely(!pskb_may_pull(skb, ghl)))
- goto out;
-
/* setup inner skb. */
skb->protocol = greh->protocol;
skb->encapsulation = 0;
+ if (unlikely(!pskb_may_pull(skb, ghl)))
+ goto out;
+
__skb_pull(skb, ghl);
skb_reset_mac_header(skb);
skb_set_network_header(skb, skb_inner_network_offset(skb));
--
1.7.10.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ipv4: fix a potential use after free in gre_offload.c
2014-10-18 9:26 [PATCH] ipv4: fix a potential use after free in gre_offload.c roy.qing.li
@ 2014-10-18 15:47 ` Eric Dumazet
2014-10-18 17:07 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Eric Dumazet @ 2014-10-18 15:47 UTC (permalink / raw)
To: roy.qing.li; +Cc: netdev, weichunc
On Sat, 2014-10-18 at 17:26 +0800, roy.qing.li@gmail.com wrote:
> From: Li RongQing <roy.qing.li@gmail.com>
>
> pskb_may_pull() may change skb->data and make greh pointer oboslete;
> so need to reassign greh;
> but since first calling pskb_may_pull already ensured that skb->data
> has enough space for greh, so move the reference of greh before second
> calling pskb_may_pull(), to avoid reassign greh.
>
> Fixes: 7a7ffbabf9("ipv4: fix tunneled VM traffic over hw VXLAN/GRE GSO NIC")
> Cc: Wei-Chun Chao <weichunc@plumgrid.com>
> Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
> ---
Acked-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ipv4: fix a potential use after free in gre_offload.c
2014-10-18 9:26 [PATCH] ipv4: fix a potential use after free in gre_offload.c roy.qing.li
2014-10-18 15:47 ` Eric Dumazet
@ 2014-10-18 17:07 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2014-10-18 17:07 UTC (permalink / raw)
To: roy.qing.li; +Cc: netdev, weichunc
From: roy.qing.li@gmail.com
Date: Sat, 18 Oct 2014 17:26:04 +0800
> From: Li RongQing <roy.qing.li@gmail.com>
>
> pskb_may_pull() may change skb->data and make greh pointer oboslete;
> so need to reassign greh;
> but since first calling pskb_may_pull already ensured that skb->data
> has enough space for greh, so move the reference of greh before second
> calling pskb_may_pull(), to avoid reassign greh.
>
> Fixes: 7a7ffbabf9("ipv4: fix tunneled VM traffic over hw VXLAN/GRE GSO NIC")
> Cc: Wei-Chun Chao <weichunc@plumgrid.com>
> Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2014-10-18 9:26 [PATCH] ipv4: fix a potential use after free in gre_offload.c roy.qing.li
2014-10-18 15:47 ` Eric Dumazet
2014-10-18 17:07 ` David Miller
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