From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9C000436377 for ; Tue, 29 Sep 2026 06:39:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790663997; cv=none; b=BREY997R2F2jj1uU8v3Jl/n5KvpG03yprBGrs530kBTwGEPV6ZLMecn6Fza57rEE0wiUyWBElirKVV4x5fHXwMeoXHDoDKGkWnFx+MH9CN16pA+Cm5DblCdxJ/fE13LN8rdTBxHcShDhjhkTPdr2hZM3wvPayiaboxcKbJaT8Hs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790663997; c=relaxed/simple; bh=JfRCyUDWwdAEnZOaxY6FNQVYF7dmWFs9oDbij31zdS8=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=WUCkV3aqYBGhArIa/0o6Y7+t3Qr372nb5di/eOLH+niiMj3uhOilfSS3MpJbFPiSPIahqea/9Wyu7IIajNaHzQlOIeunJW/6H9s92xkDzDAz6ZlXNyIUlGRWox+wcLD9M+Bd1UZ1ZSSW9FFX18wJDg1TH+JK/3diEW9O8JaR1AA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BiUArSe5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="BiUArSe5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F3AC1F000FF; Tue, 29 Sep 2026 06:39:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790663995; bh=404Qi9YhipdHavZBb5TCQTQHLX78qNk2+EO1I8dScN4=; h=Subject:To:Cc:From:Date; b=BiUArSe5oheK+xePQMHMmjvnWufrAdVgeja5pMlsSIjCorhYKqxr6KsQHdYzzXNf8 t66RpBqw/7qj8Su5pxUXQ/8xPIv7A4Q7fb/au4oWY8jk+M2lISzN2lBoEKOGiL1O+Y Uem4DzcNStOELNPr36eWScX70/2DWUdObwmVEkX8= Subject: FAILED: patch "[PATCH] vlan: require the MAC header to be present in" failed to apply to 6.18-stable tree To: xmei5@asu.edu,horms@kernel.org,kuba@kernel.org Cc: From: Date: Tue, 29 Sep 2026 08:39:52 +0200 Message-ID: <2026092952-trillion-quadrant-6e27@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x ab888242fce4f16f6c4d4c6ec53939ad36aa3b3a # git commit -s git send-email --to '' --in-reply-to '2026092952-trillion-quadrant-6e27@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ab888242fce4f16f6c4d4c6ec53939ad36aa3b3a Mon Sep 17 00:00:00 2001 From: Xiang Mei Date: Tue, 15 Sep 2026 01:31:52 -0700 Subject: [PATCH] vlan: require the MAC header to be present in __vlan_insert_inner_tag() __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 Signed-off-by: Xiang Mei Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260915083152.705309-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski 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;