From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793366511; b=VLl8XqscjslklQomya3Vyb6AVBhUtxVaAc52RAQe7MAaac6nWo5gYiBC/PkL+1I7pyfk pDLttsCV0MxttwafUL04Y8SiMw4IDoHDRmfdX4q5NcQY4OVCRu+dSkXjmWhgG86p67p/9 KXP+QsrA2VNMJLbQ8JMucED8GwXkw8eJIS2F4Zk8xVl4FPNibN8i1Fn3NazChPwvd0/ys VHWjY719K4Wyg9f7WoSrMX8/xe8cie8N7R3s/Mv1lDsL19aa8IgY58jjF428B0im28KSO UlwukEV/VrD4/YgRNEsxWads71AM2S28+FVHuxrbXjmNPeL/691KkOosylxj37tZkkw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793366511; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=9ufpfF0exPuwxlva2WzizC+kysBLY6jXA9A/YWNdq9k=; b=iD9nEU0yk5BNpz3VPLoMxN2Vzc0kZfr4jwKCnfiueYqbx7xQ+Q34bRncOkCjFOu1iWxq K3Fb6gn28D0ipZLKANrU65l2yubpP1QCNyF/L65SaoT0u3CnJ6qOl4NYsHsLtDlXtIJZj /bmWzQv2OUrjJewaQYqXBFsumFrhVZrX0lyyFZuosDvYNBkwbFAuc9e07vS54yWkc78PF JSEhYuLuyTjFx8d9jXaeouUAbiNfqFft/WLYZ+YwGNaKkXT2gIipQpdFOBtX8Kec7UxLV RkEtKLgWCfX7f8ZpKIGYIPFAxQwsAB0awfuSx+AvGUG+jVyHho/q0k+7Q4pgGSDJPRw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="gSQuO/tr"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 313EF606A31A for ; Fri, 30 Oct 2026 13:21:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gSQuO/tr Received: by smtp.kernel.org (Postfix) with ESMTPSA id 097821F000C1; Fri, 30 Oct 2026 13:21:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793366510; bh=9ufpfF0exPuwxlva2WzizC+kysBLY6jXA9A/YWNdq9k=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gSQuO/trg3l+oiPEmbmviJ4hktIms6TXfYTofD0fPUhYj5tHjrjZrJx0YFEkLUTuM tZyjF3wIW/kJkJxBPbsfd2SjQZOAPnGxeXYo80N6ihuhO5KQYK2vaVlM8HN5Z4Bynx JL9qD7pO8+pAzdTZyP3dE6qo6ueetktppS4JswCKvTRukmTsQlOobMlvpK3mI2IgbO yf4D6OV0LbqQAbCWoefczxaZpNBrFuiQXC/MGi2vU71fWoKiDorXmxtglhhNyYhg8a NvZD+yQoU4MSWVsBpqfw+Tg4cV3fcqPQZwaqmW4br30L5839XFuNhvprYqWK1BtRdV jTpVTeIekbyvg== From: Sasha Levin To: stable@vger.kernel.org Cc: Zizhen Liu , stable@kernel.org, Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18.y] net: skbuff: propagate shared-frag marker in skb_zerocopy() Date: Fri, 30 Oct 2026 09:21:48 -0400 Message-ID: <20261030132127.3663989-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026103055-chastise-denial-90ef@gregkh> References: <2026103055-chastise-denial-90ef@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zizhen Liu [ Upstream commit 79dc34beb1fdb3da79753e51e15c68591a2561fe ] skb_zerocopy() moves frag descriptors from @from into @to and takes a reference on each frag, but it does not copy skb_shinfo(from)->flags into skb_shinfo(to)->flags. A destination skb holding the same page-cache backed frags as the source therefore reports skb_has_shared_frag() as false. That breaks the invariant relied on by later in-place writers. ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(); with the marker lost, an skb that skb_zerocopy() built for nfnetlink_queue or for an openvswitch upcall is decrypted in place, letting an unprivileged user write into the page cache of a root-owned read-only file. Propagate SKBFL_SHARED_FRAG when frag descriptors are copied, as done for the other frag-transfer helpers. Fixes: af2806f8f90a ("net: Export skb_zerocopy() to zerocopy from one skb to another") Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags") Cc: stable@kernel.org Signed-off-by: Zizhen Liu Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20261022104217.1852191-1-pointerliu@126.com Signed-off-by: Jakub Kicinski [ sashal: Adjusted context in skb_zerocopy() due to missing from->unreadable propagation. ] Signed-off-by: Sasha Levin --- net/core/skbuff.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index cdce2f72fbeaf..1808bed195af1 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3883,6 +3883,8 @@ skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen) } skb_shinfo(to)->nr_frags = j; + skb_shinfo(to)->flags |= skb_shinfo(from)->flags & SKBFL_SHARED_FRAG; + return 0; } EXPORT_SYMBOL_GPL(skb_zerocopy); -- 2.53.0