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=1794419542; b=P94tkJAdvOVYGMcLylQJN0CxjSHkGijZ69cFoLce4MAlkV4Mapzd9AzX+zLoBqU4xLlw VJ8R5DhRWDXJwIiy82j4rYbbl0wYlTwPB6htwUNrUGi5UTFXjzHdqJjjlqSIyR7GX/KeQ 3DQyaN3CP9Mh7t/c3SyQT6PBdWLQvPNMkL2b+LHIHP5/QCb+SRVByZ8PAn0dzabOuQVWw NGwyXKxShrRfafdXrVjOaXuf4plzNxpdhijBllcAQLnO2YqxuonAJqPzf7nxAOhGY29XS Y+go0F6ByKgHJ6n2RWCN+5mIhiikimpNy+/58cng3GSEmrQBn8jwNg137TjVwPk2UrA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794419542; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=qjqHIXXy6piGqleiVwHgUif+/ACGSqOw+PUghCMoew8=; b=yZ/0WaY1qwBr46q9Nm0MAVcrhRnQgIZcm2wqok3p4Z6UyVA+yIxggCKd/yc59FybeYpq H/1fcwcUWaJ3YyAD5mnyaB2Y9ohF0XjULhk9TorxZndFBoZ2HBZM0KFH0MrmkCWvGhpX/ XWBY88Ae77AK/ykvm4MwIGFX+zVh492zg0sS8G3TVfIsXpVTA5HVl92HvTPw2m09eVFFo vz/QX4ctXTL01ssx0fErxt5aWmyhaK4UZzEycdqFKmnMaS6r4cVMwegoFSSBI05fp+x+U K1dGN9/cQml1HFg8jCf1NDJSXGcHT3xwzYU3JaXQ9sMS5ccdHO6SMGSEonCKP1i2htg== 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=dgR7aFyD; 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 2946D606A891 for ; Wed, 11 Nov 2026 17:52:21 +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=dgR7aFyD Received: by smtp.kernel.org (Postfix) with ESMTPSA id 154581F00A07; Wed, 11 Nov 2026 17:52:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794419541; bh=qjqHIXXy6piGqleiVwHgUif+/ACGSqOw+PUghCMoew8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dgR7aFyDAaisCpERbMXoKvjbD3pmGG81mIBKjrQ09iJeUdJdxCy2ib24ZMpEjaI+z oNZLgn4pxr5Pqooy9wwJZPSi0DtUUeyND202pi01TSQfVN3mGUeX27NcLOY0Hram9O oxOLGHA52Yv30wjHuPW9xb4O9cZqpS7L3PbbifUuqjLh4gd2bgvs9nuAfN1XmoRcWF f3f22I2lQDCYOKUVfbtGuyxWuG7321hFFPxu4EMqvG4xr3ck+m7Q8MQos8f9+FTz6d Cwsj42nffK9kcpzsG7Re+WHh/ayBmVOFjgy3FeZ3iFE/vNZQGFp4iHz8ZNN7fHGxuB eMHBFj+oGPg0A== From: Sasha Levin To: stable@vger.kernel.org Cc: Eric Dumazet , Yiming Qian , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1.y 1/2] ipmr: prevent info-leak in pmr_cache_report() Date: Wed, 11 Nov 2026 12:52:18 -0500 Message-ID: <20261111175153.3696544-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107055356-failed-6.1-94a6736bb5ab@kernel.org> References: <20261107055356-failed-6.1-94a6736bb5ab@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 948993a4f4157..f9c66ca729978 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -1087,11 +1087,12 @@ 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