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esp4: Fix udpencap for local TCP packets. 

Locally generated TCP packets are usually cloned, so we
do skb_cow_data() on this packets. After that we need to
reload the pointer to the esp header. On udpencap this
header has an offset to skb_transport_header, so take this
offset into account.

Fixes: 67d349ed60 ("net/esp4: Fix invalid esph pointer crash")
Fixes: fca11ebde3 ("esp4: Reorganize esp_output")
Reported-by: Don Bowman <db@donbowman.ca>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Steffen Klassert 2017-05-03 08:44:27 +02:00
parent f411af6822
commit 0e78a87306
1 changed files with 4 additions and 1 deletions
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5
net/ipv4/esp4.c
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@ -248,6 +248,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
u8 *tail;
u8 *vaddr;
int nfrags;
int esph_offset;
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
@ -313,11 +314,13 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
}
cow:
esph_offset = (unsigned char *)esp->esph - skb_transport_header(skb);
nfrags = skb_cow_data(skb, tailen, &trailer);
if (nfrags < 0)
goto out;
tail = skb_tail_pointer(trailer);
esp->esph = ip_esp_hdr(skb);
esp->esph = (struct ip_esp_hdr *)(skb_transport_header(skb) + esph_offset);
skip_cow:
esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);