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| author | Maher Azzouzi <maherazz04@gmail.com> | 2026-07-12 18:05:30 +0100 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2026-07-13 09:30:19 +0200 |
| commit | 21697720ff43b8dfa25b8e8d9ca7f56f4597fc80 (patch) | |
| tree | 778ba19ff2132afcb82c76fa165ca5458c416787 /net/ipv6 | |
| parent | 5d9e3bf34fec9a5d237e4b7cef4a707bc2e091bc (diff) | |
| download | linux-next-21697720ff43b8dfa25b8e8d9ca7f56f4597fc80.tar.gz linux-next-21697720ff43b8dfa25b8e8d9ca7f56f4597fc80.zip | |
esp: do not unref managed frag pages in esp_ssg_unref()
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: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
Signed-off-by: Maher Azzouzi <maherazz04@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/esp6.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c index 296b57926abb..7d216b9c59f0 100644 --- a/net/ipv6/esp6.c +++ b/net/ipv6/esp6.c @@ -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); |