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 9FA6A501285; Wed, 30 Sep 2026 17:29:31 +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=1790789372; cv=none; b=YdhigOklssCwBpx1r7KliarC5yVgBlP5KPnLY4A5YviHJU/tdb6P/oF5QtdUQBEoMT4IT35B7Kg/epqwceOR8BCVrLmwvP3XtUIxFb8912m0bjC81rbey/q06B+/qXj3SD1ssqIwOmlOUeQzHKWY0zvzk/v/1HuhELTXMVb48qs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790789372; c=relaxed/simple; bh=ThZ5pqvrlvRV6YBsC28j4smg2FwfTBjRNkSxKSXa8sM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=X10qPh3tq+fs/s11pMcM91rYw1Xg0obCsQqM5vuF/BZs5HCW4TvReoVyiamvMNueZk2+W5jSLYdb2DjJ49L3OgFKzKaN9rYOkZvTdqa6y1dgyRWvpxhYV1RU24rg13M39+VdPhbUTy3QPEDmMkjZT6eEvkV+AAlOKmYrZ/LKMUo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DZg+faam; 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="DZg+faam" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06C0A1F000FF; Wed, 30 Sep 2026 17:29:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790789371; bh=B1e3V+ujjiA+JoTb+mS+FMbOd8c4Z7OFQ85QbI/qdyQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DZg+faamJEc/shk4MlVkyYq45b9iuKMRh0BPa38t/KmPqEaAjakLZ8yPGT16qn1vt dq5pGhi0PcgmxM67AwmJd++uoyplCaUNiPat+rrReEB24hjFLDSDaSgqsiEot9v+ht jS6dBt5b5D1pYFVsbVoRfGcceABnGNkl0MEZb7z0= 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 6.12 447/877] vlan: ensure sufficient headroom in vlan_dev_hard_header() Date: Wed, 30 Sep 2026 17:22:38 +0200 Message-ID: <20260930152424.326309010@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152414.738996857@linuxfoundation.org> References: <20260930152414.738996857@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 6.12-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 e7e5b903fa8c3..61fb68fadea33 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -54,6 +54,11 @@ 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