From 0cbad673215ec8a049b7fe2ff44b0beed31b376e Mon Sep 17 00:00:00 2001
From: Philip Withnall <pwithnall@endlessos.org>
Date: Thu, 4 Feb 2021 16:12:24 +0000
Subject: [PATCH 05/11] gwinhttpfile: Avoid arithmetic overflow when
 calculating a size
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The members of `URL_COMPONENTS` (`winhttp_file->url`) are `DWORD`s, i.e.
32-bit unsigned integers. Adding to and multiplying them may cause them
to overflow the unsigned integer bounds, even if the result is passed to
`g_memdup2()` which accepts a `gsize`.

Cast the `URL_COMPONENTS` members to `gsize` first to ensure that the
arithmetic is done in terms of `gsize`s rather than unsigned integers.

Spotted by Sebastian Dröge.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #2319
---
 gio/win32/gwinhttpfile.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/gio/win32/gwinhttpfile.c
+++ b/gio/win32/gwinhttpfile.c
@@ -394,10 +394,10 @@ g_winhttp_file_resolve_relative_path (GF
   child = g_object_new (G_TYPE_WINHTTP_FILE, NULL);
   child->vfs = winhttp_file->vfs;
   child->url = winhttp_file->url;
-  child->url.lpszScheme = g_memdup2 (winhttp_file->url.lpszScheme, (winhttp_file->url.dwSchemeLength+1)*2);
-  child->url.lpszHostName = g_memdup2 (winhttp_file->url.lpszHostName, (winhttp_file->url.dwHostNameLength+1)*2);
-  child->url.lpszUserName = g_memdup2 (winhttp_file->url.lpszUserName, (winhttp_file->url.dwUserNameLength+1)*2);
-  child->url.lpszPassword = g_memdup2 (winhttp_file->url.lpszPassword, (winhttp_file->url.dwPasswordLength+1)*2);
+  child->url.lpszScheme = g_memdup2 (winhttp_file->url.lpszScheme, ((gsize) winhttp_file->url.dwSchemeLength + 1) * 2);
+  child->url.lpszHostName = g_memdup2 (winhttp_file->url.lpszHostName, ((gsize) winhttp_file->url.dwHostNameLength + 1) * 2);
+  child->url.lpszUserName = g_memdup2 (winhttp_file->url.lpszUserName, ((gsize) winhttp_file->url.dwUserNameLength + 1) * 2);
+  child->url.lpszPassword = g_memdup2 (winhttp_file->url.lpszPassword, ((gsize) winhttp_file->url.dwPasswordLength + 1) * 2);
   child->url.lpszUrlPath = wnew_path;
   child->url.dwUrlPathLength = wcslen (wnew_path);
   child->url.lpszExtraInfo = NULL;