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 97AB425F7B9; Thu, 28 May 2026 20:31:33 +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=1780000294; cv=none; b=GmuzCa+ZFs8ZjT2c/rYOhZE5GrR1tOqxhhh0ZiPV+ty742g7KtdzuWeIINohotoNoAbXev0nWEvX74bEJDWnoiBLtjXIEDigxbLoN04nvJTZsLcKgXpRU1afwGqM1qxrhN4MWaw+MU1z27p0Htx8tNQ6FjSXt3Np7RA3AW4PDnY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780000294; c=relaxed/simple; bh=7FGRltKymDszJgbwb8leSzAFWdXeA/IeLWGWJXOqrr8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CCJLclKuSHfowfP5SEMiT8IqLZItToi+kX6HwV8mBDPE7W0HODXxo00fO9NG7ipwvGa/CcqEjeQVQBWpshfmuOpqor+KXZmVRKe4PJRVPSuFEULvbKPIruOk+iWeahB3gu29QzJDxnpjRX9YvfOfEy5hwT+Ap8HAD8Q2YjYyOxI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=r2SE64VL; 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="r2SE64VL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA7D11F000E9; Thu, 28 May 2026 20:31:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780000293; bh=Capd6fK6zvGRNGrHX7SOUJN56MGZ+9F0qwn/JKZLYbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=r2SE64VLMidTnJxBd26GuLb+jlAM2dmW4REfDOToN7xsv1JcwjPlJfIvUcTgfPAok KE6oAk4g2OvwKDTBKF1gMooD7UMDYehtSO+Do//72xsuEdR0Mo5x6dNNXuYb/5AquF xCbWaW2J8kunwgVUyGejMa6/Aw4orTsIsjSyrKB8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Weiming Shi , Willem de Bruijn , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 371/377] tap: fix stack info leak in tap_ioctl() SIOCGIFHWADDR Date: Thu, 28 May 2026 21:50:09 +0200 Message-ID: <20260528194649.171916536@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194638.371537336@linuxfoundation.org> References: <20260528194638.371537336@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: Weiming Shi [ Upstream commit bddc09212c24934643bd44fc794748d2bbb3b6cd ] In the SIOCGIFHWADDR path, tap_ioctl() copies 16 bytes of an uninitialised on-stack struct sockaddr_storage to userspace via ifr_hwaddr, but netif_get_mac_address() only writes sa_family and dev->addr_len (6 for Ethernet) bytes, leaving sa_data[6..13] uninitialised. Those 8 trailing bytes leak kernel stack contents; SIOCGIFHWADDR on a macvtap chardev returns kernel .text and direct-map pointers, defeating KASLR. Initialise ss at declaration. Fixes: 3b23a32a6321 ("net: fix dev_ifsioc_locked() race condition") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260520075736.3415676-3-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/tap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index 1197f245e8737..6fd3b14273b37 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -919,11 +919,11 @@ static long tap_ioctl(struct file *file, unsigned int cmd, struct tap_queue *q = file->private_data; struct tap_dev *tap; void __user *argp = (void __user *)arg; + struct sockaddr_storage ss = {}; struct ifreq __user *ifr = argp; unsigned int __user *up = argp; unsigned short u; int __user *sp = argp; - struct sockaddr_storage ss; int s; int ret; -- 2.53.0