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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

Fix this by adding a bool parameter to esp_ssg_unref() that, when true,
unconditionally unrefs the source scatterlist frags. Since req->src is
not yet initialized by aead_request_set_crypt() at the point of the
error, the source scatterlist is obtained directly via esp_req_sg()
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:
Alessandro Schino
2026-06-05 14:22:15 +02:00
committed by Steffen Klassert
parent c381039ade
commit 26aad08a92
2 changed files with 22 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
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;
@@ -113,10 +113,13 @@ 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)
for (sg = sg_next(req->src); sg; sg = sg_next(sg))
if (already_unref || req->src != req->dst) {
struct scatterlist *src = already_unref ? esp_req_sg(aead, req) : req->src;
for (sg = sg_next(src); sg; sg = sg_next(sg))
skb_page_unref(page_to_netmem(sg_page(sg)),
skb->pp_recycle);
}
}
#ifdef CONFIG_INET_ESPINTCP
@@ -220,7 +223,7 @@ 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 +572,10 @@ 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 +607,7 @@ 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);

17
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;
@@ -130,10 +130,13 @@ 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)
for (sg = sg_next(req->src); sg; sg = sg_next(sg))
if (already_unref || req->src != req->dst) {
struct scatterlist *src = already_unref ? esp_req_sg(aead, req) : req->src;
for (sg = sg_next(src); sg; sg = sg_next(sg))
skb_page_unref(page_to_netmem(sg_page(sg)),
skb->pp_recycle);
}
}
#ifdef CONFIG_INET6_ESPINTCP
@@ -254,7 +257,7 @@ 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 +603,10 @@ 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 +639,7 @@ 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);