From patchwork Tue Apr 1 16:12:18 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Zimmermann X-Patchwork-Id: 14035144 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 93FBEC36010 for ; Tue, 1 Apr 2025 16:23:46 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 07DA110E616; Tue, 1 Apr 2025 16:23:46 +0000 (UTC) Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by gabe.freedesktop.org (Postfix) with ESMTPS id 38E6910E616 for ; Tue, 1 Apr 2025 16:23:44 +0000 (UTC) Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id F1DE821190; Tue, 1 Apr 2025 16:23:06 +0000 (UTC) Authentication-Results: smtp-out1.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id C5DD9138A5; Tue, 1 Apr 2025 16:23:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id ANv6LuoS7GdxDAAAD6G6ig (envelope-from ); Tue, 01 Apr 2025 16:23:06 +0000 From: Thomas Zimmermann To: airlied@redhat.com, sean@poorly.run, patrik.r.jakobsson@gmail.com Cc: dri-devel@lists.freedesktop.org, Thomas Zimmermann Subject: [PATCH 8/9] drm/udl: Validate length in vendor-descriptor parser Date: Tue, 1 Apr 2025 18:12:18 +0200 Message-ID: <20250401161929.283244-9-tzimmermann@suse.de> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250401161929.283244-1-tzimmermann@suse.de> References: <20250401161929.283244-1-tzimmermann@suse.de> MIME-Version: 1.0 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[]; TAGGED_RCPT(0.00)[]; ASN(0.00)[asn:25478, ipnet:::/0, country:RU] X-Rspamd-Queue-Id: F1DE821190 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Rewrite the parser for the vendor firmware descriptor with the following improvements. - Validate the key-value length given in a vendor descriptor against the length of the descriptor. The current code fails to do this and might read more bytes than available. This can lead to out-of-bounds reads of the allocated buffer. - Read raw data with helpers for unaligned data. This allows the code to run on platforms that do now support unaligned memory access by default. - Validate the pixel limit against a default value. The default comes from real-world devices. If the reported number of pixels is significantly above the limit, it is likely invalid. - Drop the obsolete print macros. There is still a warning about invalid firmware descriptors. The rest of the output is bogus. Signed-off-by: Thomas Zimmermann --- drivers/gpu/drm/udl/udl_main.c | 77 ++++++++++++++++++++++------------ 1 file changed, 51 insertions(+), 26 deletions(-) diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c index d3a04bcb65d25..b5a6b254a2028 100644 --- a/drivers/gpu/drm/udl/udl_main.c +++ b/drivers/gpu/drm/udl/udl_main.c @@ -8,6 +8,8 @@ * Copyright (C) 2009 Bernie Thompson */ +#include + #include #include #include @@ -23,10 +25,56 @@ #define WRITES_IN_FLIGHT (20) #define MAX_VENDOR_DESCRIPTOR_SIZE 256 +#define UDL_SKU_PIXEL_LIMIT_DEFAULT 2080000 + static struct urb *udl_get_urb_locked(struct udl_device *udl, long timeout); +/* + * Try to make sense of whatever we parse. Therefore return @end on + * errors, but don't fail hard. + */ +static const u8 *udl_parse_key_value_pair(struct udl_device *udl, const u8 *pos, const u8 *end) +{ + u16 key; + u8 len; + + /* read key */ + if (pos >= end - 2) + return end; + key = get_unaligned_le16(pos); + pos += 2; + + /* read value length */ + if (pos >= end - 1) + return end; + len = *pos++; + + /* read value */ + if (pos >= end - len) + return end; + switch (key) { + case 0x0200: { /* maximum number of pixels */ + unsigned int sku_pixel_limit; + + if (len < sizeof(__le32)) + break; + sku_pixel_limit = get_unaligned_le32(pos); + if (sku_pixel_limit >= 16 * UDL_SKU_PIXEL_LIMIT_DEFAULT) + break; /* almost 100 MiB, so probably bogus */ + udl->sku_pixel_limit = sku_pixel_limit; + break; + } + default: + break; + } + pos += len; + + return pos; +} + static int udl_parse_vendor_descriptor(struct udl_device *udl) { + struct drm_device *dev = &udl->drm; struct usb_device *udev = udl_to_usb_device(udl); void *buf; int ret; @@ -50,8 +98,6 @@ static int udl_parse_vendor_descriptor(struct udl_device *udl) desc = buf; desc_end = desc + len; - DRM_INFO("vendor descriptor length: %u data:%11ph\n", len, desc); - if ((desc[0] != len) || /* descriptor length */ (desc[1] != 0x5f) || /* vendor descriptor type */ (desc[2] != 0x01) || /* version (2 bytes) */ @@ -60,35 +106,14 @@ static int udl_parse_vendor_descriptor(struct udl_device *udl) goto unrecognized; desc += 5; - while (desc < desc_end) { - u8 length; - u16 key; - - key = le16_to_cpu(*((u16 *)desc)); - desc += sizeof(u16); - length = *desc; - desc++; - - switch (key) { - case 0x0200: { /* max_area */ - u32 max_area = le32_to_cpu(*((u32 *)desc)); - - DRM_DEBUG("DL chip limited to %d pixel modes\n", - max_area); - udl->sku_pixel_limit = max_area; - break; - } - default: - break; - } - desc += length; - } + while (desc < desc_end) + desc = udl_parse_key_value_pair(udl, desc, desc_end); goto success; unrecognized: /* allow udlfb to load for now even if firmware unrecognized */ - DRM_ERROR("Unrecognized vendor firmware descriptor\n"); + drm_warn(dev, "Unrecognized vendor firmware descriptor\n"); success: kfree(buf);