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 5FF3E44E025; Tue, 16 Jun 2026 15:57:53 +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=1781625474; cv=none; b=JXjwxHA+L8W1IMZu/TdwAW2rITYKD8POhIlkfDiRIDdne4ZbRtdl917AemSA2iYXyUFB765Uw3jhaoCzCei/Tfb/MwmW5ZuQy3lQ2TnBowdoxzWbudP/9ztCfo41y46pdKbqd3SVJkdEe1shSCjaHxYVI3wCIAuS7zgmN6y39A4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781625474; c=relaxed/simple; bh=uXV0m8L06y7udZsKNSLHWJ4yQ3+WOv5S8wG7hWva1BU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jWKud0sKgXBcszxsTr4QkR7uBuGC6yqR7FrhWRV3coBi5FnUMR3H7HojgtXyEApRVVdjFXujVX7kYqaBdSVozHCwnt4gpvnLLa+NufvxWIZROELLRORBL4wRtQIZsyJsFeLEtSgUCDH19XKIfDKonSHScmL2YejLHhSyQ5gHstE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2Ys7X0do; 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="2Ys7X0do" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E9FF1F000E9; Tue, 16 Jun 2026 15:57:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781625473; bh=lPKm3HDwhsxZwFmv9gyhKrSM6dqGmhTBFAxM1RnlXuU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2Ys7X0doqFeuOwfFpiFe5oep7EG+AJWd+lpZ0tmmGZGAdX5/7o3GtarIymtJUg26j c3mG+AhBdSOGM+Yr0i1f2pj6qyNezxImad5ovSKCX4cZv4u00GfaGJElbrNfhVt3cl 3Ab8jnPKZ5uMprfWHrLy18kpYGHojz7IDhrOhHKY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Davide Ornaghi , Pablo Neira Ayuso Subject: [PATCH 6.18 148/325] netfilter: nft_meta_bridge: fix stale stack leak via IIFHWADDR register Date: Tue, 16 Jun 2026 20:29:04 +0530 Message-ID: <20260616145105.092681738@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145057.827196531@linuxfoundation.org> References: <20260616145057.827196531@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: Davide Ornaghi commit c7d573551f9286100a055ef696cde6af54549677 upstream. NFT_META_BRI_IIFHWADDR declares its destination register with len = ETH_ALEN (6 bytes), which the register-init tracking rounds up to two 32-bit registers (8 bytes). nft_meta_bridge_get_eval() then does memcpy(dest, br_dev->dev_addr, ETH_ALEN), writing only 6 bytes and leaving the upper 2 bytes of the second register as uninitialised nft_do_chain() stack. A downstream load of that register span leaks those stale bytes to userspace. Zero the second register before the memcpy so the full declared span is written. Fixes: cbd2257dc96e ("netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support") Cc: stable@vger.kernel.org Signed-off-by: Davide Ornaghi Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- net/bridge/netfilter/nft_meta_bridge.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/bridge/netfilter/nft_meta_bridge.c b/net/bridge/netfilter/nft_meta_bridge.c index 7763e78abb00..219c40680260 100644 --- a/net/bridge/netfilter/nft_meta_bridge.c +++ b/net/bridge/netfilter/nft_meta_bridge.c @@ -64,6 +64,8 @@ static void nft_meta_bridge_get_eval(const struct nft_expr *expr, if (!br_dev) goto err; + /* ETH_ALEN (6) is shorter than the destination register span (8) */ + dest[1] = 0; memcpy(dest, br_dev->dev_addr, ETH_ALEN); return; default: -- 2.54.0