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 64C605683 for ; Mon, 3 Apr 2023 14:16:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC3CFC433D2; Mon, 3 Apr 2023 14:16:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680531418; bh=0vnA3WU9n71Hksc/Fk2ECnvm3tBZSD5qLPZsrYMfSA0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D7pmmxpLBD59b3q6Pj0cDjZPjHZ/105zdNd9kPpzRYPzDEw0JvUa11q050OZF6L+x KAVvK1x+qZMEVv66+6+W5bLphZxlRBV64nK7M9THadkN+6I6Tg+uwGuNUkXuDPfHQy otu5OREr7Kxo2eEqGxoYrDka8qzM4VLRTwbaRxFk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wei Chen , Helge Deller , Sasha Levin Subject: [PATCH 4.19 55/84] fbdev: tgafb: Fix potential divide by zero Date: Mon, 3 Apr 2023 16:08:56 +0200 Message-Id: <20230403140355.311986370@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140353.406927418@linuxfoundation.org> References: <20230403140353.406927418@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: Wei Chen [ Upstream commit f90bd245de82c095187d8c2cabb8b488a39eaecc ] fb_set_var would by called when user invokes ioctl with cmd FBIOPUT_VSCREENINFO. User-provided data would finally reach tgafb_check_var. In case var->pixclock is assigned to zero, divide by zero would occur when checking whether reciprocal of var->pixclock is too high. Similar crashes have happened in other fbdev drivers. There is no check and modification on var->pixclock along the call chain to tgafb_check_var. We believe it could also be triggered in driver tgafb from user site. Signed-off-by: Wei Chen Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/tgafb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/video/fbdev/tgafb.c b/drivers/video/fbdev/tgafb.c index 65ba9921506e2..9d2912947eef6 100644 --- a/drivers/video/fbdev/tgafb.c +++ b/drivers/video/fbdev/tgafb.c @@ -166,6 +166,9 @@ tgafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) { struct tga_par *par = (struct tga_par *)info->par; + if (!var->pixclock) + return -EINVAL; + if (par->tga_type == TGA_TYPE_8PLANE) { if (var->bits_per_pixel != 8) return -EINVAL; -- 2.39.2