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 2F612174CA for ; Wed, 9 Aug 2023 11:03:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A14B2C433C8; Wed, 9 Aug 2023 11:03:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691579032; bh=79oJTpMQ5Qe+GEEct3IbWLo3vsiIMe3t0neDilyZ+Jw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ocbUp9jz7FMfJE1K0z8MpdIYzhr5PYkSb9Yuo62mf06nxwO7rkJzjR8wLp7YdLJdU t5SXt/6nGtOdX62KsDjLv0CJ3SBevkyXBnMrhTIQyjbIeahiqYoqr5bsYoiUGiWs3z XXa7Qc9Lo/IdoE4bIwFcyRE3AJMlaTGytE4ngwNw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nikita Zhandarovich , Alex Deucher , Sasha Levin Subject: [PATCH 4.14 043/204] drm/radeon: fix possible division-by-zero errors Date: Wed, 9 Aug 2023 12:39:41 +0200 Message-ID: <20230809103644.012016152@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809103642.552405807@linuxfoundation.org> References: <20230809103642.552405807@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Nikita Zhandarovich [ Upstream commit 1becc57cd1a905e2aa0e1eca60d2a37744525c4a ] Function rv740_get_decoded_reference_divider() may return 0 due to unpredictable reference divider value calculated in radeon_atom_get_clock_dividers(). This will lead to division-by-zero error once that value is used as a divider in calculating 'clk_s'. While unlikely, this issue should nonetheless be prevented so add a sanity check for such cases by testing 'decoded_ref' value against 0. Found by Linux Verification Center (linuxtesting.org) with static analysis tool SVACE. v2: minor coding style fixes (Alex) In practice this should actually happen as the vbios should be properly populated. Fixes: 66229b200598 ("drm/radeon/kms: add dpm support for rv7xx (v4)") Signed-off-by: Nikita Zhandarovich Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/radeon/cypress_dpm.c | 8 ++++++-- drivers/gpu/drm/radeon/ni_dpm.c | 8 ++++++-- drivers/gpu/drm/radeon/rv740_dpm.c | 8 ++++++-- 3 files changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/radeon/cypress_dpm.c b/drivers/gpu/drm/radeon/cypress_dpm.c index 3eb7899a4035b..2c637e04dfebc 100644 --- a/drivers/gpu/drm/radeon/cypress_dpm.c +++ b/drivers/gpu/drm/radeon/cypress_dpm.c @@ -558,8 +558,12 @@ static int cypress_populate_mclk_value(struct radeon_device *rdev, ASIC_INTERNAL_MEMORY_SS, vco_freq)) { u32 reference_clock = rdev->clock.mpll.reference_freq; u32 decoded_ref = rv740_get_decoded_reference_divider(dividers.ref_div); - u32 clk_s = reference_clock * 5 / (decoded_ref * ss.rate); - u32 clk_v = ss.percentage * + u32 clk_s, clk_v; + + if (!decoded_ref) + return -EINVAL; + clk_s = reference_clock * 5 / (decoded_ref * ss.rate); + clk_v = ss.percentage * (0x4000 * dividers.whole_fb_div + 0x800 * dividers.frac_fb_div) / (clk_s * 625); mpll_ss1 &= ~CLKV_MASK; diff --git a/drivers/gpu/drm/radeon/ni_dpm.c b/drivers/gpu/drm/radeon/ni_dpm.c index fa88c18099464..701c99a551388 100644 --- a/drivers/gpu/drm/radeon/ni_dpm.c +++ b/drivers/gpu/drm/radeon/ni_dpm.c @@ -2239,8 +2239,12 @@ static int ni_populate_mclk_value(struct radeon_device *rdev, ASIC_INTERNAL_MEMORY_SS, vco_freq)) { u32 reference_clock = rdev->clock.mpll.reference_freq; u32 decoded_ref = rv740_get_decoded_reference_divider(dividers.ref_div); - u32 clk_s = reference_clock * 5 / (decoded_ref * ss.rate); - u32 clk_v = ss.percentage * + u32 clk_s, clk_v; + + if (!decoded_ref) + return -EINVAL; + clk_s = reference_clock * 5 / (decoded_ref * ss.rate); + clk_v = ss.percentage * (0x4000 * dividers.whole_fb_div + 0x800 * dividers.frac_fb_div) / (clk_s * 625); mpll_ss1 &= ~CLKV_MASK; diff --git a/drivers/gpu/drm/radeon/rv740_dpm.c b/drivers/gpu/drm/radeon/rv740_dpm.c index afd597ec50858..50290e93c79dc 100644 --- a/drivers/gpu/drm/radeon/rv740_dpm.c +++ b/drivers/gpu/drm/radeon/rv740_dpm.c @@ -251,8 +251,12 @@ int rv740_populate_mclk_value(struct radeon_device *rdev, ASIC_INTERNAL_MEMORY_SS, vco_freq)) { u32 reference_clock = rdev->clock.mpll.reference_freq; u32 decoded_ref = rv740_get_decoded_reference_divider(dividers.ref_div); - u32 clk_s = reference_clock * 5 / (decoded_ref * ss.rate); - u32 clk_v = 0x40000 * ss.percentage * + u32 clk_s, clk_v; + + if (!decoded_ref) + return -EINVAL; + clk_s = reference_clock * 5 / (decoded_ref * ss.rate); + clk_v = 0x40000 * ss.percentage * (dividers.whole_fb_div + (dividers.frac_fb_div / 8)) / (clk_s * 10000); mpll_ss1 &= ~CLKV_MASK; -- 2.39.2