From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6D49237A488 for ; Wed, 15 Apr 2026 11:48:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776253685; cv=none; b=T/rD6LuLviYoLeEwdlVTDLTlixHYZErbKJ0vDRvHpmgIm8y36fd8BNJe9oyf9f3BwCUBkyoaC98VgAOl/RDsX3SZUHrwgU/y2+D/6fKwphQVZp6vKPcrJKRpzb2g1NV1wJS8MGdrYRK3vG70/NxJXVlbNRKDzd3RfAPX26OAxqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776253685; c=relaxed/simple; bh=wYBYWS0U3wn+JrPKpLtSjLr8wl2VYLOC3vTu/H5RgJ0=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=jVVh5b1h7aIxZAxKW3F54LDb/ULKLGnj3+ZcC7kDcn4j7Kg30LU6caqZ4TxHfiMC3gBB6sgikgO75bDhHhXKjfjGAjuhgFNECnEOxQ2jV5DnTeFoGl9fayGXf67umIR7YfwhxWLgGUa63/03AFrcymsSNETJ7D9gaQVMus+Cjlg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--bsevens.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=pzzQ0EgW; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--bsevens.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pzzQ0EgW" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-488bd1ee9e7so40660005e9.1 for ; Wed, 15 Apr 2026 04:48:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1776253682; x=1776858482; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id :mime-version:date:from:to:cc:subject:date:message-id:reply-to; bh=lP3RjDHSPzb1NPTjUWSB2m8qqv8z9lgjkWSUnxmWGgM=; b=pzzQ0EgWxtT2kR2LjQW2dsV2LoCAh+7SLcufSfzCtuhYqvGqVCwLQIQGjnjL6YvCeZ HDMCKrvnK2RjLCI4m0X6OqSIFM0G/Ugv8JQHmR3ZOcz3ScEJ75h1I+lYsPWLlc2tbMip MxXKEzEma/hZml6vSi8q6P650WssvpSV8FWlagxMX6w2y+/Ae5UYMN6NJ2uLscXxXh6w LuqisoL0EuoU27iv59Vsoh86//jZKZEcWV2h9F28i3VKDiPfSxhvk+Zs9qzmLCRugtvh IZoPoT/iR9BProX8ytShB8mbKWBAbQSKKTjQWvenWtJ0SjFcvl5IZD94aOFf1F+pg2sW koaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776253682; x=1776858482; h=content-transfer-encoding:cc:to:from:subject:message-id :mime-version:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=lP3RjDHSPzb1NPTjUWSB2m8qqv8z9lgjkWSUnxmWGgM=; b=UZdW2kIq9ImyKuydi18t7GTYbRFZQvNIWb72BPKm7VYsRL9gahcuI8szdTx/MqHvwm jEUf8lieABSPs9gV4+0vqd4ri1Ge3jUMkdDGDPi1W9A6E5j6Ahr2IP7jWwBaOUqscVKN +5tmPRnLMw76971+vWm/pmYGbnJqH+LsURFoFrZ13Cg2vDsAur+zAZ3qxpbDcZQtnm1q nPTi/vxvoY4Q75blgf7ngOopw0S2h5ac7Mm4OEstOkt7kAB/rj1DJ6Wo6OuMVopdY08+ zlZSJgrNveAcYx2Lmf5gy+oH+KsXPax7KtCfq0/8OqbOyQzb8+gnHil0DoOZpZvOjT9i DqbQ== X-Gm-Message-State: AOJu0YzBP81lD8biV80UEWHT1HNsU2xDJ2zR7SjlZX/5dnw6fVckaU8Y Xz8pq8DyV8NQcMcGhrpp5+Hp2PavOYxgoTMB4N3jwNaMr6BqS/FIutsAtPe/LDgpPEtjFLr+lHe QUzzxmJOmsA== X-Received: from wmpz8.prod.google.com ([2002:a05:600c:a08:b0:485:3a2f:2f7e]) (user=bsevens job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:3acf:b0:485:35a4:939f with SMTP id 5b1f17b1804b1-488d68a8275mr254811245e9.28.1776253681593; Wed, 15 Apr 2026 04:48:01 -0700 (PDT) Date: Wed, 15 Apr 2026 11:47:51 +0000 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.54.0.rc0.605.g598a273b03-goog Message-ID: <20260415114752.1181079-1-bsevens@google.com> Subject: [PATCH] HID: mcp2221: Fix heap buffer overflow in mcp2221_raw_event() From: Benoit Sevens To: Rishi Gupta , Jiri Kosina , Benjamin Tissoires Cc: linux-i2c@vger.kernel.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, "=?UTF-8?q?Beno=C3=AEt=20Sevens?=" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable From: Beno=C3=AEt Sevens A heap buffer overflow can occur in the mcp2221_raw_event() function when handling I2C read responses. The driver failed to check if the total incoming data length fits within the originally allocated buffer `mcp->rxbuf`. Fix this by introducing `rxbuf_len` to `struct mcp2221` to keep track of the allocated buffer size. Initialize it in `mcp_i2c_smbus_read()` and `mcp_smbus_xfer()`, and ensure the copied data length combined with the current index does not exceed this length in `mcp2221_raw_event()`. Signed-off-by: Beno=C3=AEt Sevens --- drivers/hid/hid-mcp2221.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c index ef3b5c77c38e..744561e65079 100644 --- a/drivers/hid/hid-mcp2221.c +++ b/drivers/hid/hid-mcp2221.c @@ -119,6 +119,7 @@ struct mcp2221 { struct completion wait_in_report; struct delayed_work init_work; u8 *rxbuf; + int rxbuf_len; u8 txbuf[64]; int rxbuf_idx; int status; @@ -323,12 +324,14 @@ static int mcp_i2c_smbus_read(struct mcp2221 *mcp, mcp->txbuf[3] =3D (u8)(msg->addr << 1); total_len =3D msg->len; mcp->rxbuf =3D msg->buf; + mcp->rxbuf_len =3D msg->len; } else { mcp->txbuf[1] =3D smbus_len; mcp->txbuf[2] =3D 0; mcp->txbuf[3] =3D (u8)(smbus_addr << 1); total_len =3D smbus_len; mcp->rxbuf =3D smbus_buf; + mcp->rxbuf_len =3D smbus_len; } =20 ret =3D mcp_send_data_req_status(mcp, mcp->txbuf, 4); @@ -538,6 +541,7 @@ static int mcp_smbus_xfer(struct i2c_adapter *adapter, = u16 addr, =20 mcp->rxbuf_idx =3D 0; mcp->rxbuf =3D data->block; + mcp->rxbuf_len =3D sizeof(data->block); mcp->txbuf[0] =3D MCP2221_I2C_GET_DATA; ret =3D mcp_send_data_req_status(mcp, mcp->txbuf, 1); if (ret) @@ -561,6 +565,7 @@ static int mcp_smbus_xfer(struct i2c_adapter *adapter, = u16 addr, =20 mcp->rxbuf_idx =3D 0; mcp->rxbuf =3D data->block; + mcp->rxbuf_len =3D sizeof(data->block); mcp->txbuf[0] =3D MCP2221_I2C_GET_DATA; ret =3D mcp_send_data_req_status(mcp, mcp->txbuf, 1); if (ret) @@ -908,7 +913,9 @@ static int mcp2221_raw_event(struct hid_device *hdev, } if (data[2] =3D=3D MCP2221_I2C_READ_COMPL || data[2] =3D=3D MCP2221_I2C_READ_PARTIAL) { - if (!mcp->rxbuf || mcp->rxbuf_idx < 0 || data[3] > 60) { + if (!mcp->rxbuf || mcp->rxbuf_idx < 0 || + data[3] > 60 || + mcp->rxbuf_idx + data[3] > mcp->rxbuf_len) { mcp->status =3D -EINVAL; break; } --=20 2.54.0.rc0.605.g598a273b03-goog