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 698CE46C839; Fri, 7 Aug 2026 14:59:41 +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=1786114782; cv=none; b=BSCGnJ6kYP/XivbGzKdSu2okus+5fhTonSHnf63gwhae/gcLKyIkDLBF47EXDgbp5wpVEhIWkOxf/JDpOfgX/ZhiccGNPwsHjjujqgv16IR7o5v8jfPCJh2dtPiQLGl3zEHcyYz2/bHZrGkMk6yfReFS6FGDip0c+LiwdC4fd18= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786114782; c=relaxed/simple; bh=0rMW5i2/Ixg6aaZEPoFIaC5E60Q6ZBw1TiNeEx5pc9Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aP0Kv0NgJvI6MVjEo2d5ue4Kjl3zoklbbB0nAv9wEHmDPSmmAFPXs+c0qhblNOA5J2LxSFiaYkRP+3B5UrBuQq43CKPAvFIrpy4vnVTnS8PH4x8FZKhLFoCYpR8fMAjN0yJINpE1XmqMST2a4ZOL0/XKLXxFggYrXU4uZ2xZ5/A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yHpdvEkz; 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="yHpdvEkz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 852431F000E9; Fri, 7 Aug 2026 14:59:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786114781; bh=JSXf3DNkUeBqtmrv+XdX0Lfi3N6cjznbVo3T1qIU/So=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=yHpdvEkz4k/58M2dUn01GUmK7hX1PKI1xIFFWpAnbkCavWobsQ501B2iEH8p8AMHg alJSTOTbkDh7HLGya/NVyENtCeEF5FEXk1OGFAK6JqWHKshotputJktQc3kiWyTfo/ uGxwB0ns7f4n6UCwxsSrl3VBNu3NEHfg5wCHKenw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yehyeong Lee , Paolo Abeni , Sasha Levin Subject: [PATCH 6.18 005/396] net: mpls: initialize rtm_tos in mpls_getroute() Date: Fri, 7 Aug 2026 16:32:45 +0200 Message-ID: <20260807143424.391683230@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143424.272339768@linuxfoundation.org> References: <20260807143424.272339768@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yehyeong Lee [ Upstream commit 295dd295e2137e10e9a5b1891d97e0f08de76f03 ] mpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE request by filling a struct rtmsg allocated from an skb whose data area is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every field of the header except rtm_tos: r = nlmsg_data(nlh); r->rtm_family = AF_MPLS; r->rtm_dst_len = 20; r->rtm_src_len = 0; r->rtm_table = RT_TABLE_MAIN; r->rtm_type = RTN_UNICAST; r->rtm_scope = RT_SCOPE_UNIVERSE; r->rtm_protocol = rt->rt_protocol; r->rtm_flags = 0; struct rtmsg has no padding, so the one uninitialised byte rtm_tos (offset 3) is copied straight to user space on recvmsg(), leaking a byte of uninitialised heap memory. This is in contrast to mpls_dump_route(), which fills the very same header and does set rtm_tos = 0. Initialize rtm_tos to 0, matching mpls_dump_route(). Reproduced with KMSAN by adding an MPLS route and issuing a non-RTM_F_FIB_MATCH RTM_GETROUTE for its label: BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0 _copy_to_iter+0x36c/0x33f0 __skb_datagram_iter+0x196/0x12c0 skb_copy_datagram_iter+0x5b/0x210 netlink_recvmsg+0x37b/0xef0 ... Uninit was created at: __alloc_skb+0x8ca/0x10e0 mpls_getroute+0x1280/0x3a40 rtnetlink_rcv_msg+0x1138/0x15a0 ... Byte 19 of 64 is uninitialized (byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos) Fixes: 397fc9e5cefe ("mpls: route get support") Signed-off-by: Yehyeong Lee Link: https://patch.msgid.link/20260723010830.289917-1-yhlee@isslab.korea.ac.kr Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/mpls/af_mpls.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index f7f60025d042..f9b8c4d0f049 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -2468,6 +2468,7 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh, r->rtm_family = AF_MPLS; r->rtm_dst_len = 20; r->rtm_src_len = 0; + r->rtm_tos = 0; r->rtm_table = RT_TABLE_MAIN; r->rtm_type = RTN_UNICAST; r->rtm_scope = RT_SCOPE_UNIVERSE; -- 2.53.0