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 22CDE6FB5 for ; Sun, 17 Sep 2023 20:40:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8520EC433C8; Sun, 17 Sep 2023 20:40:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694983223; bh=LHhjhT46J8hTMZgenklHGDzAHgwiBQE0Gsu0ymtoIY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fbqOB89+u27YITtQ0t/tuyaOmCB54dE3utIPHQryMbLgEOedfcT185FCWxxncuy+t tmVbykRd8tArIfVHzC8QMTWef8oIpEYxNGlAHcj1aOwOY5eFSbA8sP7qTrNIy4bKfk S6QFHRaFoh4PMlNJ5FJ3fw3CA+P2FNc3Ve1kJ6gQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Aurabindo Pillai , Hamza Mahfooz , Alex Deucher Subject: [PATCH 5.15 480/511] drm/amd/display: prevent potential division by zero errors Date: Sun, 17 Sep 2023 21:15:07 +0200 Message-ID: <20230917191125.331619624@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230917191113.831992765@linuxfoundation.org> References: <20230917191113.831992765@linuxfoundation.org> User-Agent: quilt/0.67 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hamza Mahfooz commit 07e388aab042774f284a2ad75a70a194517cdad4 upstream. There are two places in apply_below_the_range() where it's possible for a divide by zero error to occur. So, to fix this make sure the divisor is non-zero before attempting the computation in both cases. Cc: stable@vger.kernel.org Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2637 Fixes: a463b263032f ("drm/amd/display: Fix frames_to_insert math") Fixes: ded6119e825a ("drm/amd/display: Reinstate LFC optimization") Reviewed-by: Aurabindo Pillai Signed-off-by: Hamza Mahfooz Signed-off-by: Alex Deucher Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c +++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c @@ -327,7 +327,9 @@ static void apply_below_the_range(struct * - Delta for CEIL: delta_from_mid_point_in_us_1 * - Delta for FLOOR: delta_from_mid_point_in_us_2 */ - if ((last_render_time_in_us / mid_point_frames_ceil) < in_out_vrr->min_duration_in_us) { + if (mid_point_frames_ceil && + (last_render_time_in_us / mid_point_frames_ceil) < + in_out_vrr->min_duration_in_us) { /* Check for out of range. * If using CEIL produces a value that is out of range, * then we are forced to use FLOOR. @@ -374,8 +376,9 @@ static void apply_below_the_range(struct /* Either we've calculated the number of frames to insert, * or we need to insert min duration frames */ - if (last_render_time_in_us / frames_to_insert < - in_out_vrr->min_duration_in_us){ + if (frames_to_insert && + (last_render_time_in_us / frames_to_insert) < + in_out_vrr->min_duration_in_us){ frames_to_insert -= (frames_to_insert > 1) ? 1 : 0; }