From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794418381; b=A4z6QMKfQTELRahKFf0Tzrw7XCR/ngU4uLzFra4uN3eOPfyvsTEFkmvieVaTE8uOvL8q 0BpDNhNk/ha0HMrMBIjYUiP1K7V2RiT4MZdWShWJVBEorPRPOg+t+LDj/ZBzdcE1tAOB+ VUJPb1v0+IRMzt//aYSFjPsNBJnLrYZlb4qv5U1XN4G6gb7rg4xYEUsZp3r4bm3QZCkwR SU3KpNMxoqodWVZbuP3Pn6S5ZFo45fCQSt5PM5v8n4GpXv3zNW1h1DSFHvQMKbPgBFNEx GCf5Y0zT6hFNE2gkr7g1k1upfyiO24sjW0qxOflOLXvPfBwElLlP1HHmLvpBxNGB36Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794418381; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=hwPLgwzYzkq5UTNhoH/QXwRXPyRS0sVP85Tr0KvPeQo=; b=VJuOzc7ie93QNW58ikLqBmkrf2XHVNmhLh8eepPTqzVEUY66hyd2LP50oRO5RKmHaKQ0 xd00DL/ZVgpDhutaNL/teqmo1jIl9YMQE+/jIyHCTpDCQ0fwUpKHKIPldOF1VB7Ashu2N NPdRleWjkdxzGFXPeTEGEkgk3AE1L3/zEXh0V0aUi5Vax+pxcoHfvN61GoWSGpMd2BU6v Ec7xPUWauIboPicgSK3Q63FNc+tsNwEwG0Pg9rDipmWtUhTqLjoN8ofxn+KTfVFzgGNLN iyttNxcFUqeNpifBMSjQFU7aIeGG8iCSn5/pR7S4L+zD642L9k/RyZhrf/1a2TCl2iQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=EIfJGN00; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81A96606A324 for ; Wed, 11 Nov 2026 17:33:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=EIfJGN00 Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5E921F00A05; Wed, 11 Nov 2026 17:33:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794418381; bh=hwPLgwzYzkq5UTNhoH/QXwRXPyRS0sVP85Tr0KvPeQo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EIfJGN006EuxWI8bVXUTcEzqKBORsZFryOBWBLhee/R10nZC1sBXGo1ZzPcGWISTQ H0gsRLutBK+VlUnlbCnXnft90BwKxiw7KoGqC6v5c3GT3kEGNIinCm/3RyIXZfSM6k EHouhgzusBllq21xQM5uL2kxT6ZJhP9BWTT+/k3m6QMcHX80b02WjexoRLp3bhvJQ3 m/80Mql4w17CoDMT2cLcPaS9iWeR0KckUggLXyyqQBKmuDaJAlh7BVPghVG/ef87L6 0FKATLa7wh15DPHDvrya1IMWCp2mAPeK97MRZYLQxeT4n7iTurxtsj8yeSOAGc8INa CWjNAp9/kjIpg== From: Sasha Levin To: stable@vger.kernel.org Cc: Eric Dumazet , Yiming Qian , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18.y 1/2] ipmr: prevent info-leak in pmr_cache_report() Date: Wed, 11 Nov 2026 12:32:58 -0500 Message-ID: <20261111173235.3591073-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107051350-failed-6.18-94a6736bb5ab@kernel.org> References: <20261107051350-failed-6.18-94a6736bb5ab@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Eric Dumazet [ Upstream commit 4f34002e2e37639133693c13a2a9977fab86880d ] Yiming Qian reported: ipmr_cache_report()` allocates a report skb with `alloc_skb(128, GFP_ATOMIC)` and appends a `struct igmphdr` using `skb_put()`. In the non-`IGMPMSG_WHOLEPKT` path it initializes only: - `igmp->type` - `igmp->code` but does not initialize: - `igmp->csum` - `igmp->group` Later, `igmpmsg_netlink_event()` copies the bytes after `sizeof(struct igmpmsg)` into the `IPMRA_CREPORT_PKT` netlink attribute and emits `RTM_NEWCACHEREPORT` on `RTNLGRP_IPV4_MROUTE_R`. As a result, 6 bytes of stale heap data from the skb head are disclosed to userspace. Let's use skb_put_zero() instead of skb_put() to fix this bug. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Yiming Qian Signed-off-by: Eric Dumazet Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260430070611.4004529-1-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 94a6736bb5ab ("ipmr: only copy pktinfo to cache reports") Signed-off-by: Sasha Levin --- net/ipv4/ipmr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index dd9ed871a1b4f..cd587d84f388e 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -1112,11 +1112,12 @@ static int ipmr_cache_report(const struct mr_table *mrt, msg->im_vif_hi = vifi >> 8; ipv4_pktinfo_prepare(mroute_sk, pkt, false); memcpy(skb->cb, pkt->cb, sizeof(skb->cb)); - /* Add our header */ - igmp = skb_put(skb, sizeof(struct igmphdr)); + /* Add our header. + * Note that code, csum and group fields are cleared. + */ + igmp = skb_put_zero(skb, sizeof(struct igmphdr)); igmp->type = assert; msg->im_msgtype = assert; - igmp->code = 0; ip_hdr(skb)->tot_len = htons(skb->len); /* Fix the length */ skb->transport_header = skb->network_header; } -- 2.53.0