From mboxrd@z Thu Jan 1 00:00:00 1970 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 25EE2C433FE for ; Tue, 18 Jan 2022 19:51:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 688D510E52E; Tue, 18 Jan 2022 19:51:14 +0000 (UTC) X-Greylist: delayed 1500 seconds by postgrey-1.36 at gabe; Tue, 18 Jan 2022 19:51:12 UTC Received: from gateway33.websitewelcome.com (gateway33.websitewelcome.com [192.185.145.216]) by gabe.freedesktop.org (Postfix) with ESMTPS id 38E0010E1BB for ; Tue, 18 Jan 2022 19:51:12 +0000 (UTC) Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 30E07EF80A for ; Tue, 18 Jan 2022 13:05:38 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 9tnVnUhDkINxB9tnVnbb2e; Tue, 18 Jan 2022 13:05:38 -0600 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=62lwA313ylYvMl776J0nmotREsLRnHNHGefb4h0dvoo=; b=PyiVKsPlAhwkbLzznyg+KBOywd sR3mIPwqE3E0G8CInbrV9M3G8iCwH7MqbVJGhkNV18tD8re3JjQ35Yw5iT63N8odXWGXNt4w2E7Qp R12bj3nDKnKpeUy6nnpQEv72BYa4D2F0GXLwSs/jytZy6I1cdm55pDlIN6bh7y0t2P9ZTFSYAXAjY QgLeAfhlb5TVG6fv+A+JHfKuJslOWE0B0sqm/ZVJi5LQzt6krt9sHb1aHrwMJ22IyotWi6ryzadzD WoRUs4BQGpRp038/cCAQKZC6sLgtAMbEFHpR3CgG71r4m3yhYcip64XkEkz60EMir+GyJFXu2QEQ4 f/FC+yGw==; Received: from [187.184.156.46] (port=26621 helo=[192.168.0.21]) by gator4166.hostgator.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1n9tnV-001SJO-46; Tue, 18 Jan 2022 13:05:37 -0600 Subject: Re: [PATCH] drm/dp: Remove common Post Cursor2 register handling To: Kees Cook , Maarten Lankhorst References: <20220105173507.2420910-1-keescook@chromium.org> From: "Gustavo A. R. Silva" Message-ID: Date: Tue, 18 Jan 2022 13:11:48 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20220105173507.2420910-1-keescook@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - lists.freedesktop.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 187.184.156.46 X-Source-L: No X-Exim-ID: 1n9tnV-001SJO-46 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([192.168.0.21]) [187.184.156.46]:26621 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes 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: Thomas Zimmermann , David Airlie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Jonathan Hunter , Thierry Reding , linux-tegra@vger.kernel.org, linux-hardening@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 1/5/22 11:35, Kees Cook wrote: > The link_status array was not large enough to read the Adjust Request > Post Cursor2 register, so remove the common helper function to avoid > an OOB read, found with a -Warray-bounds build: > > drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor': > drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds] > 59 | return link_status[r - DP_LANE0_1_STATUS]; > | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~ > drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status' > 147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE], > | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Replace the only user of the helper with an open-coded fetch and decode, > similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c. > > Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments") This should be tagged for -stable: Cc: stable@vger.kernel.org > Cc: Maarten Lankhorst > Cc: Maxime Ripard > Cc: Thomas Zimmermann > Cc: David Airlie > Cc: Daniel Vetter > Cc: dri-devel@lists.freedesktop.org > Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Thanks -- Gustavo > --- > This is the alternative to: > https://lore.kernel.org/lkml/20211203084354.3105253-1-keescook@chromium.org/ > --- > drivers/gpu/drm/drm_dp_helper.c | 10 ---------- > drivers/gpu/drm/tegra/dp.c | 11 ++++++++++- > include/drm/drm_dp_helper.h | 2 -- > 3 files changed, 10 insertions(+), 13 deletions(-) > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 23f9073bc473..c9528aa62c9c 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -144,16 +144,6 @@ u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE], > } > EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset); > > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE], > - unsigned int lane) > -{ > - unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2; > - u8 value = dp_link_status(link_status, offset); > - > - return (value >> (lane << 1)) & 0x3; > -} > -EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor); > - > static int __8b10b_clock_recovery_delay_us(const struct drm_dp_aux *aux, u8 rd_interval) > { > if (rd_interval > 4) > diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c > index 70dfb7d1dec5..f5535eb04c6b 100644 > --- a/drivers/gpu/drm/tegra/dp.c > +++ b/drivers/gpu/drm/tegra/dp.c > @@ -549,6 +549,15 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link, > { > struct drm_dp_link_train_set *adjust = &link->train.adjust; > unsigned int i; > + u8 post_cursor; > + int err; > + > + err = drm_dp_dpcd_read(link->aux, DP_ADJUST_REQUEST_POST_CURSOR2, > + &post_cursor, sizeof(post_cursor)); > + if (err < 0) { > + DRM_ERROR("failed to read post_cursor2: %d\n", err); > + post_cursor = 0; > + } > > for (i = 0; i < link->lanes; i++) { > adjust->voltage_swing[i] = > @@ -560,7 +569,7 @@ static void drm_dp_link_get_adjustments(struct drm_dp_link *link, > DP_TRAIN_PRE_EMPHASIS_SHIFT; > > adjust->post_cursor[i] = > - drm_dp_get_adjust_request_post_cursor(status, i); > + (post_cursor >> (i << 1)) & 0x3; > } > } > > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h > index 472dac376284..fdf3cf6ccc02 100644 > --- a/include/drm/drm_dp_helper.h > +++ b/include/drm/drm_dp_helper.h > @@ -1528,8 +1528,6 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI > int lane); > u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE], > int lane); > -u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE], > - unsigned int lane); > > #define DP_BRANCH_OUI_HEADER_SIZE 0xc > #define DP_RECEIVER_CAP_SIZE 0xf >