From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f47.google.com (mail-oo1-f47.google.com [209.85.161.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B021B248881 for ; Tue, 15 Sep 2026 08:32:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789461122; cv=none; b=A/Tizn1CvgOVFI0SmNqL1IIh6sxjpiV6wEBvYKqtZ3StvWngTGOnQzm7QXyJPNKyj3avIhW5VUkxMitI86EtYwhdNjfe40Cnp07cgUoRcWX5yo6AOP5NEe33zGX6nUyAULx4hUmHKv/MWEw2J7F7FMc5+VLkmz7+he5WcyWZ+n0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789461122; c=relaxed/simple; bh=Kyljv4Ok0VOKC1521YIj/5MqOlgJleHDXLfDK8e9KT4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KClsn6GSf0OeldQpuu5OfN8pQHYcLMKMawCX3yIYshAgMNMHV8DUyuEbYp0ax/2qOQ95VGpnw0hAl7aao8mtrf140jCw5vefiyLxvd/KSmmFGy+1r6P/GMn7cl5fnO0qJtwpg8jlh6QqPle5h0UujHzJUy+2cPGVafh87aBjX3E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asu.edu; spf=pass smtp.mailfrom=asu.edu; dkim=pass (2048-bit key) header.d=asu.edu header.i=@asu.edu header.b=CtmKId3R; arc=none smtp.client-ip=209.85.161.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=asu.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=asu.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=asu.edu header.i=@asu.edu header.b="CtmKId3R" Received: by mail-oo1-f47.google.com with SMTP id 006d021491bc7-6b1334a3b16so2970160eaf.1 for ; Tue, 15 Sep 2026 01:32:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=asu.edu; s=google; t=1789461119; x=1790065919; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=nfGU+d0Ce1ol/Tm6wjF345/Jrj4e+fpsFxiynd3zRTo=; b=CtmKId3RdfumA/w6zh32NfLeMv7G7HjRGzsGUTA0XZrv393XmRI2/zcF7VkSqUAlWf yNwtTI4N66M0tg4+x8powKLGzGYF83QXsCtc5sO1F3BGxu6bkCWn4O1fOXQywNYH+crF owvoW+M+4nJqVobywFWMLZ+rdi9tjR0iu5spiOy7v5oIcwzv1xXrv4DIqdbnqwoN39hV 5pSkTI19I9RQM+MiwJkjOPGgWKcZxGJ8tan0Q4VyUbHromhVr4XQfmXYDWr7QN5mh2te NWNX6NF+D6GtbdqlAfggAhqlyMCYBYEgfcurQS87Ipn6poRqIQtuiYfPlwEqGrKRRbCi g0TA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789461119; x=1790065919; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=nfGU+d0Ce1ol/Tm6wjF345/Jrj4e+fpsFxiynd3zRTo=; b=kCi4uyQTyuRYeLlyTBQ8zEKNLK3uYy9Ywn5MjXsVnvQ24H1DyDD03DUwixUovtQ6kx bdvJfLI1UeVoYZIVvAKvy0mchqjx22ewQYRTYQz6Kx4gB86NgpWSlGhDguDyxnmdY88O iI1c8SL+gnICVD7ASKYN+N27f6xZBY63TZdKdMljeM/m4eAJphtd9obDNQtFsIq/vQxE fpbuwC6dC48O1nBlHBgNLIbfkn1a1aBlpVFaU4XgvhQ+AXkzeUGUIYRc3ZCO3689m4vg A5F7QnVfqTWF3grW7ywcE5c47WWXYWTggA0HELcQ2zb8+j0ScvrDKm5pTBD4kV5DwGQO 6f0w== X-Gm-Message-State: AFuF++nb8LAF9uWsMko5NymWI1FyzIfE616djiydcrpwX80co0hNiXu7 cuyXrLzhEUaxvUUK73ZM5Y5I9lmcL+svB/cKrbX/vGAMNLjyn8xvKtUS9+//fdmY2A== X-Gm-Gg: AYBFou38YvZn4g+37zVeUNGj+GKKgarFA4oQSC0Fibl9hM7s8J/hi8WBlfKIg/hJ63f RtYK/6ew3ZNJrEzjZYa/IZpa5VHMKdFfSN129AVmWMxukx4MQ9TIwzKjdYk53XpfMNBOmxahN97 D4Xrv9CB0JMhWBYPUgarL8RhHZzaLPSsmid9QT0xbaUGtzT7n/g1iSVvUcAHaq386EiinuXNXi4 7ldjhVaqaHLzxNn4UMaupFuiq9gTvGaDS4x22nj31otGQGl4ps6+HSfghRi039sRqEVdV13fBrN taytRrBSc3DmWtoDdsCMVOV3VMGkSHVb9cvdcBXHhmG3sBicTM6jUKEMPm64MkLZJkMHPxNmzxZ z3yOEs/+GBkbUF5/CGN1nnlejV0zDYT91WftjMJqFeM1LHZV2GmnTvuueAGK31W/Q9JnixHiVjG ftokPBnBi4Z7bgArZykc5oH52z7WeqrSbeDT2Y1tsvHMDTaBEEH0zSpEz8/wTwMH97UDX0ZB+O/ YN6SsXYh4u8oKSul/p+HMtSEwNjmAIHajtX3ymP6Z0GOnKDdmcT5kda X-Received: by 2002:a05:6820:190b:b0:6b7:83d6:2925 with SMTP id 006d021491bc7-6c5423435dbmr3269444eaf.40.1789461119455; Tue, 15 Sep 2026 01:31:59 -0700 (PDT) Received: from xps.tailc0aff1.ts.net (149-169-99-5.nat.asu.edu. [149.169.99.5]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-14382741839sm13579723c88.6.2026.09.15.01.31.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Sep 2026 01:31:59 -0700 (PDT) From: Xiang Mei To: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jakub@cloudflare.com, Xiang Mei , stable@vger.kernel.org, co+0ea1ac045375cf05@bugs.sh Subject: [PATCH net] vlan: require the MAC header to be present in __vlan_insert_inner_tag() Date: Tue, 15 Sep 2026 01:31:52 -0700 Message-ID: <20260915083152.705309-1-xmei5@asu.edu> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __vlan_insert_inner_tag() only guarantees head room via skb_cow_head(), never that mac_len bytes of MAC header are present. Its ETH_HLEN wrappers - __vlan_insert_tag() under skb_vlan_push(), and vlan_insert_tag() under validate_xmit_vlan() on the generic transmit path - therefore rewrite the first 16 bytes at skb->data: a 12-byte memmove plus two 2-byte stores at +12 and +14. No caller supplies the bound, while the pop helpers use skb_ensure_writable()/pskb_may_pull(). An IFF_TUN device has hard_header_len == 0, so packet_snd() accepts a one-byte AF_PACKET/SOCK_RAW frame. The first vlan push only sets a hwaccel tag; the next - clsact "action vlan push" or bpf_skb_vlan_push() - enters the helper with skb->len still 1. The head comes from skbuff_small_head without __GFP_ZERO, so each push drags bytes from beyond skb->tail into the frame. After three the one-byte send leaves as 13 bytes carrying 11 bytes of uninitialised slab: 0000: 5a b3 62 12 80 88 ff ff 00 b3 62 12 81 `------------------------------' only 0x5a was sent; the rest is slab, here the top 56 bits of a linear-map address Require the MAC header the helper rewrites to be present, so such a frame is dropped rather than transmitted. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reported-by: co+0ea1ac045375cf05@bugs.sh Assisted-by: LLM Signed-off-by: Xiang Mei --- include/linux/if_vlan.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index 20cc16ea4e5a..4846032bf4ff 100644 --- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -365,6 +365,9 @@ static inline int __vlan_insert_inner_tag(struct sk_buff *skb, const u8 meta_len = mac_len > ETH_TLEN ? skb_metadata_len(skb) : 0; struct vlan_ethhdr *veth; + if (unlikely(!pskb_may_pull(skb, mac_len))) + return -EINVAL; + if (skb_cow_head(skb, meta_len + VLAN_HLEN) < 0) return -ENOMEM; -- 2.43.0