From 4a4ecc32b160e93ee1e37e5617a0197e2d022643 Mon Sep 17 00:00:00 2001
From: Armin Novak <armin.novak@thincast.com>
Date: Thu, 4 Nov 2021 11:07:41 +0100
Subject: [PATCH] Add checks for bitmap and glyph width/heigth values

CVE-2021-41160

https://github.com/FreeRDP/FreeRDP/pull/7349

Signed-off-by: Felipe Borges <felipeborges@gnome.org>
---
 libfreerdp/core/orders.c  | 14 ++++++++++++
 libfreerdp/core/surface.c | 45 +++++++++++++++++++++++++++++++++++++++
 libfreerdp/core/update.c  |  7 ++++++
 3 files changed, 66 insertions(+)

diff --git a/libfreerdp/core/orders.c b/libfreerdp/core/orders.c
index 74870fae6..44d23a61a 100644
--- a/libfreerdp/core/orders.c
+++ b/libfreerdp/core/orders.c
@@ -1848,6 +1848,13 @@ static BOOL update_read_fast_glyph_order(wStream* s, const ORDER_INFO* orderInfo
 			new_cb = ((glyph->cx + 7) / 8) * glyph->cy;
 			new_cb += ((new_cb % 4) > 0) ? 4 - (new_cb % 4) : 0;
 
+			if ((glyph->cx == 0) || (glyph->cy == 0))
+			{
+				WLog_ERR(TAG, "GLYPH_DATA_V2::cx=%" PRIu32 ", GLYPH_DATA_V2::cy=%" PRIu32,
+				         glyph->cx, glyph->cy);
+				return FALSE;
+			}
+
 			if (fastGlyph->cbData < new_cb)
 				return FALSE;
 
@@ -2825,6 +2832,13 @@ update_read_create_offscreen_bitmap_order(wStream* s,
 	Stream_Read_UINT16(s, create_offscreen_bitmap->cy); /* cy (2 bytes) */
 	deleteList = &(create_offscreen_bitmap->deleteList);
 
+	if ((create_offscreen_bitmap->cx == 0) || (create_offscreen_bitmap->cy == 0))
+	{
+		WLog_ERR(TAG, "Invalid OFFSCREEN_DELETE_LIST: cx=%" PRIu16 ", cy=%" PRIu16,
+		         create_offscreen_bitmap->cx, create_offscreen_bitmap->cy);
+		return FALSE;
+	}
+
 	if (deleteListPresent)
 	{
 		UINT32 i;
diff --git a/libfreerdp/core/surface.c b/libfreerdp/core/surface.c
index d5c709885..ca89d230c 100644
--- a/libfreerdp/core/surface.c
+++ b/libfreerdp/core/surface.c
@@ -21,6 +21,8 @@
 #include "config.h"
 #endif
 
+#include <assert.h>
+
 #include <freerdp/utils/pcap.h>
 #include <freerdp/log.h>
 
@@ -62,6 +64,13 @@ static BOOL update_recv_surfcmd_bitmap_ex(wStream* s, TS_BITMAP_DATA_EX* bmp)
 	Stream_Read_UINT16(s, bmp->height);
 	Stream_Read_UINT32(s, bmp->bitmapDataLength);
 
+	if ((bmp->width == 0) || (bmp->height == 0))
+	{
+		WLog_ERR(TAG, "invalid size value width=%" PRIu16 ", height=%" PRIu16, bmp->width,
+		         bmp->height);
+		return FALSE;
+	}
+
 	if ((bmp->bpp < 1) || (bmp->bpp > 32))
 	{
 		WLog_ERR(TAG, "invalid bpp value %" PRIu32 "", bmp->bpp);
@@ -85,6 +94,39 @@ static BOOL update_recv_surfcmd_bitmap_ex(wStream* s, TS_BITMAP_DATA_EX* bmp)
 	return TRUE;
 }
 
+static BOOL update_recv_surfcmd_is_rect_valid(const rdpContext* context,
+                                              const SURFACE_BITS_COMMAND* cmd)
+{
+	assert(context);
+	assert(context->settings);
+	assert(cmd);
+
+	/* We need a rectangle with left/top being smaller than right/bottom.
+	 * Also do not allow empty rectangles. */
+	if ((cmd->destTop >= cmd->destBottom) || (cmd->destLeft >= cmd->destRight))
+	{
+		WLog_WARN(TAG,
+		          "Empty surface bits command rectangle: %" PRIu16 "x%" PRIu16 "-%" PRIu16
+		          "x%" PRIu16,
+		          cmd->destLeft, cmd->destTop, cmd->destRight, cmd->destBottom);
+		return FALSE;
+	}
+
+	/* The rectangle needs to fit into our session size */
+	if ((cmd->destRight > context->settings->DesktopWidth) ||
+	    (cmd->destBottom > context->settings->DesktopHeight))
+	{
+		WLog_WARN(TAG,
+		          "Invalid surface bits command rectangle: %" PRIu16 "x%" PRIu16 "-%" PRIu16
+		          "x%" PRIu16 " does not fit %" PRIu32 "x%" PRIu32,
+		          cmd->destLeft, cmd->destTop, cmd->destRight, cmd->destBottom,
+		          context->settings->DesktopWidth, context->settings->DesktopHeight);
+		return FALSE;
+	}
+
+	return TRUE;
+}
+
 static BOOL update_recv_surfcmd_surface_bits(rdpUpdate* update, wStream* s, UINT16 cmdType)
 {
 	SURFACE_BITS_COMMAND cmd = { 0 };
@@ -98,6 +140,9 @@ static BOOL update_recv_surfcmd_surface_bits(rdpUpdate* update, wStream* s, UINT
 	Stream_Read_UINT16(s, cmd.destRight);
 	Stream_Read_UINT16(s, cmd.destBottom);
 
+	if (!update_recv_surfcmd_is_rect_valid(update->context, &cmd))
+		goto fail;
+
 	if (!update_recv_surfcmd_bitmap_ex(s, &cmd.bmp))
 		goto fail;
 
diff --git a/libfreerdp/core/update.c b/libfreerdp/core/update.c
index ebb82fc2d..e137c3de8 100644
--- a/libfreerdp/core/update.c
+++ b/libfreerdp/core/update.c
@@ -99,6 +99,13 @@ static BOOL update_read_bitmap_data(rdpUpdate* update, wStream* s, BITMAP_DATA*
 	Stream_Read_UINT16(s, bitmapData->flags);
 	Stream_Read_UINT16(s, bitmapData->bitmapLength);
 
+	if ((bitmapData->width == 0) || (bitmapData->height == 0))
+	{
+		WLog_ERR(TAG, "Invalid BITMAP_DATA: width=%" PRIu16 ", height=%" PRIu16, bitmapData->width,
+		         bitmapData->height);
+		return FALSE;
+	}
+
 	if (bitmapData->flags & BITMAP_COMPRESSION)
 	{
 		if (!(bitmapData->flags & NO_BITMAP_COMPRESSION_HDR))
-- 
2.32.0