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=1794419112; b=v/MBIfgi7S8Pal/n+H37GMiH3kVeJP+xFcfHjqvYUZLEC9GNn0ghmeR7PauMBitJzw/s lQAnr8qz74QHym2ShhYHvuO6knKRqXHK3HAUNBy2HQDjAMlwYR/67iptSZxXw2NCDJrDa s6upK9g1bK2LGdVoKUF0BoK3w5LH2sdrSFe+xgVedu7fy8hmw3WvviUXi/CupUs1RK1xx 22FGZTEJf4iuIZrqsVftuXxuJiQnGG686dbWGWvz8UehrOoKKQKFfhmmaylyNdwR1qgXU xoRLiG6Tbcwejni7+fSjxyFLYcvYn1aGbXGdziQhs1e9/dvAoU5z3cKLBtcmJhuO77Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794419112; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=JCcZl0NKO4r6xS5iodOTiKldicOGYB07k7RVkaSj9Zg=; b=oE8a1n69QFRJ5br1qwoQODxkAsAZRv057KJHu98IQA9IJx5+TRf3Blc2/FQ7dSTw3s8l x5o0j5sydxSmqDgGIkgSibxRv7Ax5Dg2d4RGYFrb8nibe3GG5MgrvYWE4FEWxnbpKRjJ1 08F/mW68U41Tt8SewbiBQ6rDF8KkTuZTcIXMWo3IIQSSbsQz8j5Fb54F79SgoaCgGbLku YrMFxKYlDjmzMoB7jUK6U3sNIEp45IXjYlKH1kBiUrEwOyKpq+Sj9pa4Gq4jey1JJYcal 8R/TMZCTco7e3JqqisOdPxFHzH3VyAVICTSTFQT+TWnLFevewGFQXpFbGRPdW9DncKQ== 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=obDPY6bq; 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 172B5606B4D4 for ; Wed, 11 Nov 2026 17:45:11 +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=obDPY6bq Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED6AD1F00A05; Wed, 11 Nov 2026 17:45:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794419111; bh=JCcZl0NKO4r6xS5iodOTiKldicOGYB07k7RVkaSj9Zg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=obDPY6bq33zvVT2GPiLQ/4fnkJi36W4cgCVU9+yIItIBKyUsJSCRl6oqdGubW80EV Bnm34AoIh5i9kaKaVrLS1pvUYeCb+hiV0enzG6hiJ5iCEfZqQCnX36BvGaJyb6BjWR 9xITDPuaX5119J889QpL+Mr43Usy1u3zIBnn13MuqdWH2p1mzjIYxI3f8MNGn5Mcoq W9XvUVsnB69MY1zYd+GbE5HlRoDfZPXMKHDgtDg3avcJtPNbVP05MX853UkWpWjxZO OtKQdSyaAeji5iFUSpO3Je0LSDUAVm7+DLlu1tl7mP/AiIIOffitwyFqhrYX/nriSO wd7yRQm0/Tu2g== From: Sasha Levin To: stable@vger.kernel.org Cc: Eric Dumazet , Yiming Qian , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6.y 1/2] ipmr: prevent info-leak in pmr_cache_report() Date: Wed, 11 Nov 2026 12:45:08 -0500 Message-ID: <20261111174441.3663023-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107053830-failed-6.6-94a6736bb5ab@kernel.org> References: <20261107053830-failed-6.6-94a6736bb5ab@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 edd2413edff99..391b0152d6c85 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