From patchwork Thu Dec 14 20:37:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 13493615 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 870B5C4332F for ; Thu, 14 Dec 2023 20:38:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id ADD9F10E25E; Thu, 14 Dec 2023 20:38:20 +0000 (UTC) Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4FE1E10E25E for ; Thu, 14 Dec 2023 20:38:13 +0000 (UTC) Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-6cecb004339so5095359b3a.3 for ; Thu, 14 Dec 2023 12:38:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1702586292; x=1703191092; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=RCuUsFQR6lp6/7dcHWOPjNe2VLvS+gov+CkK1fWJuUI=; b=YBsVD4O5IMzoM5Y2X+jIDLMmPq5WXmz0A8GZdJOpyLMGiBoyZX+t8lJOq3hHCpYwU9 aAHF4FCGZb3D2bfykcYo+y2FvvjcKYiF9mlYceFcNnV11TFcu6NV27i/Psg837pe6Jsl Ag90J1hkNf9Dye6u0qPlx7ZJJUstv1SJ2tL1Y= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702586292; x=1703191092; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=RCuUsFQR6lp6/7dcHWOPjNe2VLvS+gov+CkK1fWJuUI=; b=CslwgVKcVrIptr+t0IT+u6LbAzCfKxYMjb2ChwHhsb+BH6GLBvblClZYU5u7jfIoey EJnGpnlBdOm6WH6m1pTgZY5mqOnGMXmoUqtTZ1Bw2Zir0cU6A/LfCGH9r+BL5342waqN XNdG6FHzQGkG7Q9OyKaduyqFleI5INbQz/aMEnLPQJBMGR1smNia4TrN4wrZllTEPVXB mRRO4fyDjW7w6nWPN3fn3VtDzMngVTmYsvtbmH+nyZRvNAdhB2Oh8u1kCWWTe5Equrje 8/CGP10wvie+9UVHCH1sXaRJTY35VMP5FqLTic7KAjHgOAk7iqh10IdWkKE0ZyndlXUU 17NA== X-Gm-Message-State: AOJu0Yx9tb5+pPjU/kuYJQoppfIs7KaCBHgq4YoNWgEOEwIzN2otoxCa 87EyWvClh8WsbVrZNnd5f8pjDckr0gglXzQcUsW4vNMc X-Google-Smtp-Source: AGHT+IEqBO+G2ecwBpTD5DnxvMh1rm2t6Nq3fzf3H6fhqeSmAfh6caWQ9m9jlmzPR4UB2NwbehmaMA== X-Received: by 2002:a05:6a21:3398:b0:18c:2287:29cf with SMTP id yy24-20020a056a21339800b0018c228729cfmr6588631pzb.40.1702586292209; Thu, 14 Dec 2023 12:38:12 -0800 (PST) Received: from tictac2.mtv.corp.google.com ([2620:15c:9d:2:9d0c:9bd0:17f6:8236]) by smtp.gmail.com with ESMTPSA id y18-20020a170902b49200b001cfc2e0a82fsm12799081plr.26.2023.12.14.12.38.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Dec 2023 12:38:11 -0800 (PST) From: Douglas Anderson To: dri-devel@lists.freedesktop.org Subject: [PATCH v3 2/2] drm/bridge: ti-sn65dsi86: Never store more than msg->size bytes in AUX xfer Date: Thu, 14 Dec 2023 12:37:52 -0800 Message-ID: <20231214123752.v3.2.I7b83c0f31aeedc6b1dc98c7c741d3e1f94f040f8@changeid> X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog In-Reply-To: <20231214123752.v3.1.I9d1afcaad76a3e2c0ca046dc4adbc2b632c22eda@changeid> References: <20231214123752.v3.1.I9d1afcaad76a3e2c0ca046dc4adbc2b632c22eda@changeid> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Maxime Ripard , Neil Armstrong , Robert Foss , Andrzej Hajda , Thomas Zimmermann , Jonas Karlman , Sam Ravnborg , Douglas Anderson , Jernej Skrabec , Stephen Boyd , Laurent Pinchart , Guenter Roeck , linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" For aux reads, the value `msg->size` indicates the size of the buffer provided by `msg->buffer`. We should never in any circumstances write more bytes to the buffer since it may overflow the buffer. In the ti-sn65dsi86 driver there is one code path that reads the transfer length from hardware. Even though it's never been seen to be a problem, we should make extra sure that the hardware isn't increasing the length since doing so would cause us to overrun the buffer. Fixes: 982f589bde7a ("drm/bridge: ti-sn65dsi86: Update reply on aux failures") Signed-off-by: Douglas Anderson Reviewed-by: Guenter Roeck Reviewed-by: Stephen Boyd --- (no changes since v2) Changes in v2: - Updated patch subject to match ps8640 patch. drivers/gpu/drm/bridge/ti-sn65dsi86.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 9095d1453710..62cc3893dca5 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -527,6 +527,7 @@ static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux, u32 request_val = AUX_CMD_REQ(msg->request); u8 *buf = msg->buffer; unsigned int len = msg->size; + unsigned int short_len; unsigned int val; int ret; u8 addr_len[SN_AUX_LENGTH_REG + 1 - SN_AUX_ADDR_19_16_REG]; @@ -600,7 +601,8 @@ static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux, } if (val & AUX_IRQ_STATUS_AUX_SHORT) { - ret = regmap_read(pdata->regmap, SN_AUX_LENGTH_REG, &len); + ret = regmap_read(pdata->regmap, SN_AUX_LENGTH_REG, &short_len); + len = min(len, short_len); if (ret) goto exit; } else if (val & AUX_IRQ_STATUS_NAT_I2C_FAIL) {