From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E396C336EDE; Mon, 20 Apr 2026 15:43:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776699832; cv=none; b=j/TcdVoceJxlPWQSTa7mfCc+CnrE8NIVN8lpSlMnszrJdWJaY4qcGynvX9kiZWo/BQ9HBVvetOTNcl35zbcWD5pRa+LSCKU9LJnHtit2BESCiA/42GRYKpeOGhFul7s81cjLFJj7UrkOX7vQnV2HEIwdWtfLz8brbmCGxLnt4Ck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776699832; c=relaxed/simple; bh=4NgmwA0+lLhnM1RLJ3LQSvFiI1g8OspyQNREUc3YyxA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=a4HmCEq/gGVvXLW8Yc/U05dzai373/5GQ6NlKz/TXI4ycA7n67reby7IjSBzXOPH/eVyw4Jep1Emzs1MSoCRhMYz8IQXX9BIy4PgH8Zcq/yTOIxX7zw6lkLZzCV2Q22uIRy3p3xxkYcD9riy+fkuLTRtq3cPoNAxFqpDGC1lD8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zYvqYXyQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zYvqYXyQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79896C2BCB4; Mon, 20 Apr 2026 15:43:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776699831; bh=4NgmwA0+lLhnM1RLJ3LQSvFiI1g8OspyQNREUc3YyxA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zYvqYXyQfruTAgQafOOyxXngv3pxNov0nUZHRuAcr+0cRPdTP62/Djr/xqwwAStLt r18QrjjsJR1QdPvBHRK/1sqRlGS85lJWli/ZgfqvCWBYfxWzwf16EmkzIzycg8WqlL yh9skAPZwCwxRqdsqHHsMtz1thIb2CMEngUVLzZE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable Subject: [PATCH 7.0 15/76] usb: gadget: f_ncm: validate minimum block_len in ncm_unwrap_ntb() Date: Mon, 20 Apr 2026 17:41:26 +0200 Message-ID: <20260420153911.377388912@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420153910.810034134@linuxfoundation.org> References: <20260420153910.810034134@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 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman commit 8f993d30b95dc9557a8a96ceca11abed674c8acb upstream. The block_len read from the host-supplied NTB header is checked against ntb_max but has no lower bound. When block_len is smaller than opts->ndp_size, the bounds check of: ndp_index > (block_len - opts->ndp_size) will underflow producing a huge unsigned value that ndp_index can never exceed, defeating the check entirely. The same underflow occurs in the datagram index checks against block_len - opts->dpe_size. With those checks neutered, a malicious USB host can choose ndp_index and datagram offsets that point past the actual transfer, and the skb_put_data() copies adjacent kernel memory into the network skb. Fix this by rejecting block lengths that cannot hold at least the NTB header plus one NDP. This will make block_len - opts->ndp_size and block_len - opts->dpe_size both well-defined. Commit 8d2b1a1ec9f5 ("CDC-NCM: avoid overflow in sanity checking") fixed a related class of issues on the host side of NCM. Fixes: 2b74b0a04d3e ("USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb()") Cc: stable Assisted-by: gregkh_clanker_t1000 Link: https://patch.msgid.link/2026040753-baffle-handheld-624d@gregkh Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_ncm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1210,8 +1210,8 @@ parse_ntb: block_len = get_ncm(&tmp, opts->block_length); /* (d)wBlockLength */ - if (block_len > ntb_max) { - INFO(port->func.config->cdev, "OUT size exceeded\n"); + if ((block_len < opts->nth_size + opts->ndp_size) || (block_len > ntb_max)) { + INFO(port->func.config->cdev, "Bad block length: %#X\n", block_len); goto err; }