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 9451518C332; Wed, 30 Sep 2026 16:57:02 +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=1790787423; cv=none; b=QVTZmuuToLVwKFAK6KGDYMxeZewBbgsZ61FBzrCIQKwomTIV2VjwpNK2xM7uKAZlPVcw6ksvipgvw/wwfiTgDgTN3rQedF3fu1FnuwSkEWbhXAsXTJCIn+CONr2yweYOrGKU2wFIXQnBY7oBfFevO9bEAXCZlgo+4aQqHiYMniw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790787423; c=relaxed/simple; bh=L2aCkJjqScPWVNfoXkzrgEiapXDtJb+5CEhps2xqTYY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RrOdX33lgoTbTimM8CUW1Yn3rFa76TYcAympEYXnD6U0tWA1o6PaqRhB6RLM6OmCV2mzQKEFgjT4ESSA+1DZNYD5t8DHQ9iJr6m5bLA7zWQtCDeW+H2EbAHJ1vugSlB5wePUXLvKklw1WlTgBWpcbq5oKsYkD5m8JBGcZPEwHFw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nwZbWPES; 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="nwZbWPES" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 258E21F000FF; Wed, 30 Sep 2026 16:57:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790787422; bh=MMtGCboId9qHqzzIax4k2r7R1KwLGvTSqMgzfDs7IgM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nwZbWPESQUoFHyAgFF2+XD1ulj1lFmg49VsGQ/JBuTrsesf11AlKiYml992K3TcCl MNaeevFvfPrmAjVZRkYoTGAcrq+8ED6VT3tovFS8j7W2b6XBt05EUA/4tHRRa7pD+N djtf/ZtccumF9oscIaTQnRVnSTkzGaqFOl3usIiY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zixuan Chai , Hangbin Liu , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 7.2 225/457] vlan: ensure sufficient headroom in vlan_dev_hard_header() Date: Wed, 30 Sep 2026 17:25:30 +0200 Message-ID: <20260930152350.905786343@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152346.024115587@linuxfoundation.org> References: <20260930152346.024115587@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit cd5dd68267c4238795fadaf02b3575ca3f8a6500 ] Callers that only reserve ETH_HLEN or less (such as llc_alloc_frame()), or skbs allocated before dynamic device/headroom changes (e.g. toggling VLAN_FLAG_REORDER_HDR or bonding/team switching slaves), can reach vlan_dev_hard_header() with insufficient headroom and trigger skb_under_panic(). Use skb_cow_head() in vlan_dev_hard_header() when VLAN_FLAG_REORDER_HDR is not set to ensure sufficient headroom for the VLAN header(s) and the underlying device hard header. Use READ_ONCE() to read dev->hard_header_len and dev->needed_headroom as they can be updated concurrently under RTNL (e.g. in vlan_transfer_features()) while vlan_dev_hard_header() runs locklessly on the transmit path. Also avoid LL_RESERVED_SPACE(dev) here so that the extra HH_DATA_MOD alignment padding does not trigger unnecessary pskb_expand_head() reallocations on inner stacked VLAN devices after the outer VLAN header has been pushed. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Zixuan Chai Closes: https://lore.kernel.org/netdev/cover.1789987105.git.petalzu987@gmail.com/ Link: https://lore.kernel.org/netdev/179022851638.2160803.1808206741379444999@kernel.org/ Cc: Hangbin Liu Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260924082951.1599377-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/8021q/vlan_dev.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c index 2859cbac3f266..c949c6a829456 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -55,6 +55,11 @@ static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev, int rc; if (!(vlan->flags & VLAN_FLAG_REORDER_HDR)) { + unsigned int hlen = READ_ONCE(dev->hard_header_len) + + READ_ONCE(dev->needed_headroom); + + if (skb_cow_head(skb, hlen) < 0) + return -ENOMEM; vhdr = skb_push(skb, VLAN_HLEN); vlan_tci = vlan->vlan_id; -- 2.53.0