diff options
| author | Pavel Begunkov <asml.silence@gmail.com> | 2026-05-28 19:43:53 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-05-29 12:55:27 -0700 |
| commit | ff6e798c2eac3ebd0501ad7e796f583fab928de8 (patch) | |
| tree | d3a7c5c004e21d60fe354db604d20e7d1e3f4f32 | |
| parent | 9c7da87c2dc860bb17ca1ece942495d28b1ce3b9 (diff) | |
net: skbuff: fix pskb_carve leaking zcopy pages
When SKBFL_MANAGED_FRAG_REFS is set, frag pages are not refcounted but
their lifetime is controlled by the attached ubuf_info. To make a copy
of the skb_shared_info, we either should clear the flag and reference
the frags, or keep the flag and have frags unreferenced.
pskb_carve_inside_header() and pskb_carve_inside_nonlinear() don't
follow the rule and thus can leak page references. Let's clear
SKBFL_MANAGED_FRAG_REFS from the original skb to fix it. It's the
simplest way to address it, but there are more performant ways to do
that if it ever becomes a problem.
Link: https://lore.kernel.org/all/20260523085809.26331-1-nvminh232@clc.fitus.edu.vn/
Fixes: 753f1ca4e1e50 ("net: introduce managed frags infrastructure")
Reported-by: Minh Nguyen <minhnguyen.080505@gmail.com>
Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/1e2086aa69217d7f9c8da3d38f5be7160f1b4cd1.1779993185.git.asml.silence@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/core/skbuff.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 0d3cc115f2e7..c02f0a507ba8 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -6823,6 +6823,11 @@ static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off, skb_copy_from_linear_data_offset(skb, off, data, new_hlen); skb->len -= off; + /* Remove SKBFL_MANAGED_FRAG_REFS instead of trying to honour it + * while refcounting frags below. + */ + skb_zcopy_downgrade_managed(skb); + memcpy((struct skb_shared_info *)(data + size), skb_shinfo(skb), offsetof(struct skb_shared_info, @@ -6936,6 +6941,11 @@ static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off, return -ENOMEM; size = SKB_WITH_OVERHEAD(size); + /* Remove SKBFL_MANAGED_FRAG_REFS instead of trying to honour it + * while refcounting frags below. + */ + skb_zcopy_downgrade_managed(skb); + memcpy((struct skb_shared_info *)(data + size), skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0])); if (skb_orphan_frags(skb, gfp_mask)) { |