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esp: fix page frag reference leak on skb_to_sgvec failure

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In esp_output_tail(), when esp->inplace is false, the old skb page frags
are replaced with a new page from the xfrm page_frag cache. The source
scatterlist (sg) is built from the old frags before the replacement, and
esp_ssg_unref() is responsible for releasing the old page references
after the crypto operation completes.

However, if the second skb_to_sgvec() call (which builds the destination
scatterlist from the new page) fails, the code jumps to error_free which
only calls kfree(tmp). The old page frag references captured in the
source scatterlist are never released:

  1. sg[] is built from old frags via skb_to_sgvec() (no extra get_page)
  2. nr_frags is set to 1 and frag[0] is replaced with the new page
  3. Second skb_to_sgvec() fails -> goto error_free
  4. kfree(tmp) frees the sg[] memory but old frags are not unref'd
  5. kfree_skb() only releases frag[0] (the new page), not the old ones

Fix this by adding a bool parameter to esp_ssg_unref() that, when true,
unconditionally unrefs the source scatterlist frags without checking
req->src and req->dst, since those fields are not yet initialized by
aead_request_set_crypt() at the point of the error. Existing callers
pass false to preserve the original behavior.

The same issue exists in both esp4 and esp6 as the code is identical.

Fixes: cac2661c53 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a ("esp6: Avoid skb_cow_data whenever possible")

Signed-off-by: Alessandro Schino <7991aleschino@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
e521588 2026-05-20 09:27:17 +02:00 committed by Steffen Klassert
parent 79d8be2623
commit 2982e599ff
2 changed files with 14 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/ipv4/esp4.c
View File

@ -96,7 +96,7 @@ static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
__alignof__(struct scatterlist));
}
static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb, bool already_unref)
{
struct crypto_aead *aead = x->data;
int extralen = 0;
@ -113,7 +113,7 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
/* Unref skb_frag_pages in the src scatterlist if necessary.
* Skip the first sg which comes from skb->data.
*/
if (req->src != req->dst)
if (already_unref || req->src != req->dst)
for (sg = sg_next(req->src); sg; sg = sg_next(sg))
skb_page_unref(page_to_netmem(sg_page(sg)),
skb->pp_recycle);
@ -220,7 +220,7 @@ static void esp_output_done(void *data, int err)
}
tmp = ESP_SKB_CB(skb)->tmp;
esp_ssg_unref(x, tmp, skb);
esp_ssg_unref(x, tmp, skb, false);
kfree(tmp);
if (xo && (xo->flags & XFRM_DEV_RESUME)) {
@ -569,8 +569,10 @@ int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
err = skb_to_sgvec(skb, dsg,
(unsigned char *)esph - skb->data,
assoclen + ivlen + esp->clen + alen);
if (unlikely(err < 0))
if (unlikely(err < 0)) {
esp_ssg_unref(x, tmp, skb, true);
goto error_free;
}
}
if ((x->props.flags & XFRM_STATE_ESN))
@ -602,7 +604,7 @@ int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
}
if (sg != dsg)
esp_ssg_unref(x, tmp, skb);
esp_ssg_unref(x, tmp, skb, false);
if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
err = esp_output_tail_tcp(x, skb);

12
net/ipv6/esp6.c
View File

@ -113,7 +113,7 @@ static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
__alignof__(struct scatterlist));
}
static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb, bool already_unref)
{
struct crypto_aead *aead = x->data;
int extralen = 0;
@ -130,7 +130,7 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
/* Unref skb_frag_pages in the src scatterlist if necessary.
* Skip the first sg which comes from skb->data.
*/
if (req->src != req->dst)
if (already_unref || req->src != req->dst)
for (sg = sg_next(req->src); sg; sg = sg_next(sg))
skb_page_unref(page_to_netmem(sg_page(sg)),
skb->pp_recycle);
@ -254,7 +254,7 @@ static void esp_output_done(void *data, int err)
}
tmp = ESP_SKB_CB(skb)->tmp;
esp_ssg_unref(x, tmp, skb);
esp_ssg_unref(x, tmp, skb, false);
kfree(tmp);
esp_output_encap_csum(skb);
@ -600,8 +600,10 @@ int esp6_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
err = skb_to_sgvec(skb, dsg,
(unsigned char *)esph - skb->data,
assoclen + ivlen + esp->clen + alen);
if (unlikely(err < 0))
if (unlikely(err < 0)) {
esp_ssg_unref(x, tmp, skb, true);
goto error_free;
}
}
if ((x->props.flags & XFRM_STATE_ESN))
@ -634,7 +636,7 @@ int esp6_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info
}
if (sg != dsg)
esp_ssg_unref(x, tmp, skb);
esp_ssg_unref(x, tmp, skb, false);
if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
err = esp_output_tail_tcp(x, skb);