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 9B3533B0ACE; Wed, 30 Sep 2026 19:11:10 +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=1790795471; cv=none; b=qrE2dL0Nhu3Fw0KHNMDdDN0Y8JrvJEHr/ZTMDhnxkRHG9x8GYl2p/y9ySlmpzPu5XPGfEoum6kJCxRZxVlMgQMeCEczQ8aWs2j6rJDq5RcAK6V+FABHJb8FafO+aQOxIL9K/1dDPVOMqH1c9I96z2UZDKGzP88iqk1X/VvyPUY0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795471; c=relaxed/simple; bh=yE60G2OIdqGw0fov+g4W9r6/EhN1Pc7LGLL3hSSelDc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nceiVoyOcXYrqz9sREzq0O7TjDQ1qDO/MSNs8m8sBqHXRaVCdxfZi1lhacVWliFjRXt9o/Q/rib3AwLyUvRyEuoLGQtyUeg9p6TzBY5MQgIX97Wj+3rtNVgrUUiZ5XHH6lDJog8DD5Ne1ORAk5IZKlbSAU68ajFBfYipHsk5EKk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GHu4XUCh; 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="GHu4XUCh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF5BA1F000FF; Wed, 30 Sep 2026 19:11:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790795470; bh=4HyTGTGHio4ooytNJda8MCO2Eg8BrfvR+6G4EEV7Tkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GHu4XUCh2/fMEOit+r+Z+OQ5g9NG8eWjFJLol/U8QOMJXu+6oqb5DshjT48P3E24G yYwl/pUjh0PPjDG08uxERNZ+S1qkcnjyQGaHaruyZeG16B9M6O84FHEzGunXNUxYuP XGQZvFA0/eBdghNc/ibFDytHxDNonZuexVx76W3Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 0574/1193] vxlan: initialize _md in vxlan_xmit_one() Date: Wed, 30 Sep 2026 17:20:58 +0200 Message-ID: <20260930152446.993251637@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit be83178bfc44588f6e3adb827ed874c683193466 ] If a VXLAN device is configured with both VXLAN_F_COLLECT_METADATA and VXLAN_F_GBP, and a packet is transmitted through it using an external ip_tunnel_info that lacks the IP_TUNNEL_VXLAN_OPT_BIT flag, md is left pointing to the uninitialized _md stack variable: if (test_bit(IP_TUNNEL_VXLAN_OPT_BIT, info->key.tun_flags)) { if (info->options_len < sizeof(*md)) goto drop; md = ip_tunnel_info_opts(info); } Because IP_TUNNEL_VXLAN_OPT_BIT is not set, md is not updated and remains pointing to _md. Later, vxlan_build_skb() is called with md, which eventually calls vxlan_build_gbp_hdr(): if (vxflags & VXLAN_F_GBP) vxlan_build_gbp_hdr(vxh, md); Inside vxlan_build_gbp_hdr(), md->gbp is read: if (!md->gbp) return; gbp = (struct vxlanhdr_gbp *)vxh; ... if (md->gbp & VXLAN_GBP_DONT_LEARN) gbp->dont_learn = 1; If the stack contains garbage, this causes: 1) VXLAN_HF_GBP flag to be spuriously set in the VXLAN header. 2) gbp->dont_learn and gbp->policy_applied to be set from stack bits. 3) gbp->policy_id to receive 16 bits of uninitialized kernel stack data, leaking it onto the wire. Fix this by zero-initializing _md. If IP_TUNNEL_VXLAN_OPT_BIT is not present, md->gbp remains 0, and vxlan_build_gbp_hdr() returns early without modifying the VXLAN header. Fixes: ee122c79d422 ("vxlan: Flow based tunneling") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260906180111.1973188-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/vxlan/vxlan_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index bbffd73772362..7be4a32728107 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -2365,7 +2365,7 @@ void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, struct ip_tunnel_key key; struct vxlan_dev *vxlan = netdev_priv(dev); const struct iphdr *old_iph; - struct vxlan_metadata _md; + struct vxlan_metadata _md = {}; struct vxlan_metadata *md = &_md; unsigned int pkt_len = skb->len; __be16 src_port = 0, dst_port; -- 2.53.0