mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-08-31 12:52:29 -04:00
Code Issues Packages Projects Releases Wiki Activity

esp: do not unref managed frag pages in esp_ssg_unref()

Browse Source 
esp_ssg_unref() releases the page references held on the source
scatterlist after the AEAD operation completes.  It calls
skb_page_unref() on every frag page for an out-of-place transform
(req->src != req->dst), and in the error path of esp_output_tail()
(already_unref == true) on the request's own scatterlist.

This is wrong when the skb carries managed frags
(SKBFL_MANAGED_FRAG_REFS).  Managed frags are owned by a zerocopy ubuf
and the skb does not hold a per-frag page reference; io_uring SEND_ZC
with a registered buffer attaches the bvec pages this way via
io_sg_from_iter().  The rest of the stack honours this invariant:
skb_release_data() skips the per-frag unref when SKBFL_MANAGED_FRAG_REFS
is set, and skb_zcopy_managed() is the guard used at the other unref
sites.

esp_ssg_unref() is missing that guard, so for a managed-frag skb it
drops a page reference the skb never acquired.  This can underflow the
page reference count and free a page that is still in use.

Guard the function with skb_zcopy_managed() so both unref paths are
skipped for managed-frag skbs, matching skb_release_data().

Fixes: cac2661c53 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a ("esp6: Avoid skb_cow_data whenever possible")
Signed-off-by: Maher Azzouzi <maherazz04@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Maher Azzouzi
2026-07-12 18:05:30 +01:00
committed by Steffen Klassert
parent 5d9e3bf34f
commit 21697720ff
2 changed files with 14 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
net/ipv4/esp4.c
View File

@@ -104,6 +104,13 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb,
struct aead_request *req;
struct scatterlist *sg;
/* Managed frags are owned by the zerocopy ubuf; the skb holds no
* per-frag page reference, so we must not drop one here. Mirrors
* the SKBFL_MANAGED_FRAG_REFS handling in skb_release_data().
*/
if (skb_zcopy_managed(skb))
return;
if (x->props.flags & XFRM_STATE_ESN)
extralen += sizeof(struct esp_output_extra);

7
net/ipv6/esp6.c
View File

@@ -121,6 +121,13 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb,
struct aead_request *req;
struct scatterlist *sg;
/* Managed frags are owned by the zerocopy ubuf; the skb holds no
* per-frag page reference, so we must not drop one here. Mirrors
* the SKBFL_MANAGED_FRAG_REFS handling in skb_release_data().
*/
if (skb_zcopy_managed(skb))
return;
if (x->props.flags & XFRM_STATE_ESN)
extralen += sizeof(struct esp_output_extra);