From 1909d8ea9297287f1ff6862968608dcf06e60523 Mon Sep 17 00:00:00 2001
From: Philip Withnall <pwithnall@gnome.org>
Date: Thu, 4 Dec 2025 16:37:19 +0000
Subject: [PATCH] gfileattribute: Fix integer overflow calculating escaping for
 byte strings

The number of invalid characters in the byte string (characters which
would have to be percent-encoded) was only stored in an `int`, which
gave the possibility of a long string largely full of invalid
characters overflowing this and allowing an attacker-controlled buffer
size to be allocated.

This could be triggered by an attacker controlled file attribute (of
type `G_FILE_ATTRIBUTE_TYPE_BYTE_STRING`), such as
`G_FILE_ATTRIBUTE_THUMBNAIL_PATH` or `G_FILE_ATTRIBUTE_STANDARD_NAME`,
being read by user code.

Spotted by Codean Labs.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Fixes: #3845

CVE: CVE-2025-14512
Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/glib/-/commit/1909d8ea9297287f1ff6862968608dcf06e60523]
Signed-off-by: Peter Marko <peter.marko@siemens.com>
---
 gio/gfileattribute.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/gio/gfileattribute.c b/gio/gfileattribute.c
index c6fde60fa..d3083e5bd 100644
--- a/gio/gfileattribute.c
+++ b/gio/gfileattribute.c
@@ -20,6 +20,7 @@
 
 #include "config.h"
 
+#include <stdint.h>
 #include <string.h>
 
 #include "gfileattribute.h"
@@ -271,11 +272,12 @@ valid_char (char c)
   return c >= 32 && c <= 126 && c != '\\';
 }
 
+/* Returns NULL on error */
 static char *
 escape_byte_string (const char *str)
 {
   size_t i, len;
-  int num_invalid;
+  size_t num_invalid;
   char *escaped_val, *p;
   unsigned char c;
   const char hex_digits[] = "0123456789abcdef";
@@ -293,7 +295,12 @@ escape_byte_string (const char *str)
     return g_strdup (str);
   else
     {
-      escaped_val = g_malloc (len + num_invalid*3 + 1);
+      /* Check for overflow. We want to check the inequality:
+       * !(len + num_invalid * 3 + 1 > SIZE_MAX) */
+      if (num_invalid >= (SIZE_MAX - len) / 3)
+        return NULL;
+
+      escaped_val = g_malloc (len + num_invalid * 3 + 1);
 
       p = escaped_val;
       for (i = 0; i < len; i++)
