xen: patch with XSA-512

Xen Security Advisory CVE-2026-79604 / XSA-512
                               version 3

             oxenstored: Unbounded accumulation of watches

Oxenstored maintains two datastructures about watches; one global trie,
and one hashtable tracked per domain.  When a xenbus reconnect is
requested, watches are not cleared out of the global trie.

A guest can cause unbounded memory usage in oxenstored.  This can lead
to a system-wide DoS.

This is the Xen oxenstored patch.

https://xenbits.xenproject.org/xsa/advisory-512.html

Signed-off-by: Fernando Rodrigues <alpha@sigmasquadron.net>

(cherry picked from commit a36b0d5d62)

pkgs/by-name/xe/xen/package.nix

@@ -200,6 +200,15 @@ stdenv.mkDerivation (finalAttrs: {
       url = "https://xenbits.xenproject.org/xsa/xsa511-4.20.patch";
       hash = "sha256-rQTQ0UmDKo5Oi8THUHfb8W6/1OY2S3VEowmJf7Tb+1o=";
     })
+
+    (fetchpatch {
+      url = "https://xenbits.xenproject.org/xsa/xsa512-1.patch";
+      hash = "sha256-Xky7ddRSd1d+Y/voEmsyiyMsU7NX/WM2/yOviaLv5gU=";
+    })
+    (fetchpatch {
+      url = "https://xenbits.xenproject.org/xsa/xsa512-2.patch";
+      hash = "sha256-4LgqC1F22kFjiVWgiSb1hZazbBF2Fziiif0Scv+ynho=";
+    })
   ]
   ++ optionals (versionOlder finalAttrs.version "4.21") [
     # Patch `libxl` to search for `qemu-system-i386` properly.