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esp: Fix possible buffer overflow in ESP transformation

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commit ebe48d368e97d007bfeb76fcb065d6cfc4c96645 upstream.

The maximum message size that can be send is bigger than
the  maximum site that skb_page_frag_refill can allocate.
So it is possible to write beyond the allocated buffer.

Fix this by doing a fallback to COW in that case.

v2:

Avoid get get_order() costs as suggested by Linus Torvalds.

Fixes: cac2661c53 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a ("esp6: Avoid skb_cow_data whenever possible")
Reported-by: valis <sec@valis.email>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steffen Klassert
2022-03-07 13:11:39 +01:00
committed by Greg Kroah-Hartman
parent 96340cdd55
commit 9248694dac
4 changed files with 13 additions and 0 deletions
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5
net/ipv6/esp6.c
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@@ -483,6 +483,7 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
unsigned int allocsz;
if (x->encap) {
int err = esp6_output_encap(x, skb, esp);
@@ -491,6 +492,10 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
return err;
}
allocsz = ALIGN(skb->data_len + tailen, L1_CACHE_BYTES);
if (allocsz > ESP_SKB_FRAG_MAXSIZE)
goto cow;
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
nfrags = 1;