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 57CCB19E98B; Mon, 23 Dec 2024 16:13:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734970402; cv=none; b=PHMGahUnIpz6mI0AuTqMfmHg/IwDKR6wJk+a68FkHPVOEEa7VFJcAPGFTbHjYKmjb6cEHgmuYsc5PfWxNlxA6mU+4mUWKWNaVqD9NIgTGKZ7mrKDSzd5fWa0gRKsacMfGsk2aP85A4ii6MBefNmJKxsqbjfg7Xq1EvlA64ztvZ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734970402; c=relaxed/simple; bh=0/3/DoYOsdoDUtbPUXYVigoKSE0LZmq0uJK4EPRbaJ4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TNMmQ4T1NIPkqXFUQHbt1mydoUJzwDQT5uQsIMh9EzBPbedn9kPkqLceZqotChq4pDB7Bp5FymD0L91MjdjraN28jVlojLs4m7vYPVTtCVR9PGcq8ASpv1BGZNA6NDWy5EdasvIuBk0ax1IqMWiIC5G1VcC/U/hJ/XuRuKpkyoc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cXJcGQfo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cXJcGQfo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87D8EC4CED3; Mon, 23 Dec 2024 16:13:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734970402; bh=0/3/DoYOsdoDUtbPUXYVigoKSE0LZmq0uJK4EPRbaJ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cXJcGQfooQOsEt7tjwWsgzb0d7R3niZi278vtG/TN3a2TPORcyPqBi5ILm6fnVDKX LYZM2lju884T4kaeT9dgR41ueqCMNO+YiA+40zur3XmG4QJc9Dn7w6pYPxjwK9e2qN neu8qXLxYTnTOk3uA2LvJ3rTJjlxm/PKnZF9E0OU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+622bba18029bcde672e1@syzkaller.appspotmail.com, =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Jani Nikula Subject: [PATCH 6.6 073/116] drm/modes: Avoid divide by zero harder in drm_mode_vrefresh() Date: Mon, 23 Dec 2024 16:59:03 +0100 Message-ID: <20241223155402.402267487@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241223155359.534468176@linuxfoundation.org> References: <20241223155359.534468176@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ville Syrjälä commit 9398332f23fab10c5ec57c168b44e72997d6318e upstream. drm_mode_vrefresh() is trying to avoid divide by zero by checking whether htotal or vtotal are zero. But we may still end up with a div-by-zero of vtotal*htotal*... Cc: stable@vger.kernel.org Reported-by: syzbot+622bba18029bcde672e1@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=622bba18029bcde672e1 Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20241129042629.18280-2-ville.syrjala@linux.intel.com Reviewed-by: Jani Nikula Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_modes.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/drm_modes.c +++ b/drivers/gpu/drm/drm_modes.c @@ -1285,14 +1285,11 @@ EXPORT_SYMBOL(drm_mode_set_name); */ int drm_mode_vrefresh(const struct drm_display_mode *mode) { - unsigned int num, den; + unsigned int num = 1, den = 1; if (mode->htotal == 0 || mode->vtotal == 0) return 0; - num = mode->clock; - den = mode->htotal * mode->vtotal; - if (mode->flags & DRM_MODE_FLAG_INTERLACE) num *= 2; if (mode->flags & DRM_MODE_FLAG_DBLSCAN) @@ -1300,6 +1297,12 @@ int drm_mode_vrefresh(const struct drm_d if (mode->vscan > 1) den *= mode->vscan; + if (check_mul_overflow(mode->clock, num, &num)) + return 0; + + if (check_mul_overflow(mode->htotal * mode->vtotal, den, &den)) + return 0; + return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(num, 1000), den); } EXPORT_SYMBOL(drm_mode_vrefresh);