From 57a1d3a487ea0ee0c0df44d46a21d0a95897bb25 Mon Sep 17 00:00:00 2001
From: gbaraldi <baraldigabriel@gmail.com>
Date: Mon, 28 Apr 2025 17:18:06 -0300
Subject: [PATCH 1/2] Make build_id.lo more random

---
 src/module.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/module.c b/src/module.c
index 4c685ca574523..e7cb3918c7352 100644
--- a/src/module.c
+++ b/src/module.c
@@ -481,7 +481,8 @@ static jl_module_t *jl_new_module__(jl_sym_t *name, jl_module_t *parent)
     m->istopmod = 0;
     m->uuid = uuid_zero;
     static unsigned int mcounter; // simple counter backup, in case hrtime is not incrementing
-    m->build_id.lo = jl_hrtime() + (++mcounter);
+    // TODO: this is used for ir decompression and is liable to hash collisions so use more of the bits
+    m->build_id.lo = bitmix(jl_hrtime() + (++mcounter), jl_rand());
     if (!m->build_id.lo)
         m->build_id.lo++; // build id 0 is invalid
     m->build_id.hi = ~(uint64_t)0;

From eb401f365f33b1def3b91a7e61d5d76b40b32ab6 Mon Sep 17 00:00:00 2001
From: gbaraldi <baraldigabriel@gmail.com>
Date: Wed, 30 Apr 2025 18:33:00 -0300
Subject: [PATCH 2/2] Make loading fail if it detects a buildid collision

---
 src/staticdata.c       |  6 +++++-
 src/staticdata_utils.c | 16 +++++++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/staticdata.c b/src/staticdata.c
index a8ebf1d9bc345..df38ad1fc0277 100644
--- a/src/staticdata.c
+++ b/src/staticdata.c
@@ -4410,7 +4410,11 @@ static jl_value_t *jl_restore_package_image_from_stream(ios_t *f, jl_image_t *im
             JL_SIGATOMIC_END();
 
             // Add roots to methods
-            jl_copy_roots(method_roots_list, jl_worklist_key((jl_array_t*)restored));
+            int failed = jl_copy_roots(method_roots_list, jl_worklist_key((jl_array_t*)restored));
+            if (failed != 0) {
+                jl_printf(JL_STDERR, "Error copying roots to methods from Module: %s\n", pkgname);
+                abort();
+            }
             // Insert method extensions and handle edges
             int new_methods = jl_array_nrows(extext_methods) > 0;
             if (!new_methods) {
diff --git a/src/staticdata_utils.c b/src/staticdata_utils.c
index 95a64964eccba..c3f6a7e98a550 100644
--- a/src/staticdata_utils.c
+++ b/src/staticdata_utils.c
@@ -736,17 +736,31 @@ static void jl_activate_methods(jl_array_t *external, jl_array_t *internal, size
     }
 }
 
-static void jl_copy_roots(jl_array_t *method_roots_list, uint64_t key)
+static int jl_copy_roots(jl_array_t *method_roots_list, uint64_t key)
 {
     size_t i, l = jl_array_nrows(method_roots_list);
+    int failed = 0;
     for (i = 0; i < l; i+=2) {
         jl_method_t *m = (jl_method_t*)jl_array_ptr_ref(method_roots_list, i);
         jl_array_t *roots = (jl_array_t*)jl_array_ptr_ref(method_roots_list, i+1);
         if (roots) {
             assert(jl_is_array(roots));
+            if (m->root_blocks) {
+                // check for key collision
+                uint64_t *blocks = jl_array_data(m->root_blocks, uint64_t);
+                size_t nx2 = jl_array_nrows(m->root_blocks);
+                for (size_t i = 0; i < nx2; i+=2) {
+                    if (blocks[i] == key) {
+                        // found duplicate block
+                        failed = -1;
+                    }
+                }
+            }
+
             jl_append_method_roots(m, key, roots);
         }
     }
+    return failed;
 }
 
 static jl_value_t *read_verify_mod_list(ios_t *s, jl_array_t *depmods)