`parallel/test-snapshot-reproducible` fails when ASLR is enabled

Commencez par test/parallel/test-snapshot-reproducible.js, en particulier par l’assertion de la ligne 47. Reproduisez le problème avec ./configure && make et Linux ASLR défini sur 1 ou 2, puis comparez le snapshot généré avec ASLR désactivé. Le travail est terminé lorsque l’échec est corrigé ou réduit à une cause documentée propre à V8 ou à l’environnement, avec une prochaine étape claire.

Testing main on linux:

# sysctl -w kernel.randomize_va_space=2
$ ./configure && make && ./node test/parallel/test-snapshot-reproducible.js
node:internal/assert/utils:146
  throw error;
  ^

AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
+ actual - expected
... Skipped lines

  [
    '#include <cstddef>',
    '#include "env.h"',
    '#include "node_snapshot_builder.h"',
    '#include "v8.h"',
...
    'namespace node {',
+   'static const char v8_snapshot_blob_data[] = {4,0,0,0,1,0,0,0,43,108,-20,-8,-43,-25,-94,-55,49,52,46,54,46,50,48,50,46,51,52,45,110,111,100,101,46,50,49,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  // 0',
-   'static const char v8_snapshot_blob_data[] = {4,0,0,0,1,0,0,0,-99,103,75,7,-43,-25,-94,-55,49,52,46,54,46,50,48,50,46,51,52,45,110,111,100,101,46,50,49,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  // 0',
    '0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,16,10,23,0,64,8,25,0,72,114,29,0,8,107,30,0,-120,98,31,0,-40,88,32,0,-85,6,-34,-64,-96,9,23,0,-83,24,96,0,0,0,0,86,0,0,0,96,0,0,0,0,  // 1',
    '0,0,0,0,96,0,0,0,0,0,0,0,0,96,0,0,0,0,-53,1,0,0,96,0,0,0,0,-84,1,0,0,96,0,0,0,0,-64,2,0,0,96,0,0,0,0,0,0,0,0,96,0,0,0,0,-30,0,0,0,11,5,24,98,0,2,  // 2',
    '5,24,34,1,2,5,24,-30,1,2,5,24,-94,2,2,5,24,98,3,2,5,24,34,4,2,5,24,-30,4,2,5,24,-94,5,2,5,24,98,6,2,5,24,34,7,2,5,24,-30,7,2,5,24,-94,8,2,5,24,98,9,2,1,76,7,101,  // 3',
    '15,69,64,97,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,64,98,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,64,96,0,0,0,0,0,0,0,0,7,-123,2,64,96,0,0,0,  // 4',
    '0,8,0,0,0,-127,0,91,64,1,20,83,69,97,0,0,0,0,96,0,0,0,0,0,0,0,1,0,0,0,93,1,20,83,69,97,0,0,0,0,96,0,0,0,0,0,0,0,1,0,0,0,93,1,20,83,69,97,0,0,0,0,96,0,  // 5',
...
    '26,-87,22,26,-11,27,26,93,28,26,101,28,26,105,34,26,69,37,26,73,37,26,77,37,26,81,37,26,85,37,26,89,37,26,93,37,26,97,37,26,101,37,26,-87,43,26,-83,43,26,-71,43,1,20,86,98,0,0,0,0,3,0,0,0,0,  // 42996',
+   '0,0,0,1,0,0,0,0,0,0,0,14,0,0,0,64,91,31,0,6,-71,2,5,24,66,66,4,4,8,95,4,73,33,11,15,0,-3,15,0,8,6,0,0,-3,15,4,96,6,-86,-127,-107,44,127,0,0,24,0,0,0,0,0,0,0,47,  // 42997',
+   '0,0,0,0,0,0,0,0,-107,26,0,8,8,0,0,-107,26,4,64,8,-102,-74,95,5,0,0,0,16,0,0,0,0,0,0,0,0,-99,39,0,8,2,0,0,-99,39,4,-64,2,-102,-74,95,5,0,0,0,48,0,0,0,0,0,0,0,51,  // 42998',
+   '0,0,0,0,0,0,0,52,0,0,0,0,0,0,0,53,0,0,0,0,0,0,0,54,0,0,0,0,0,0,0,0,-67,49,0,8,7,0,0,-67,49,4,64,7,-102,-74,95,5,0,0,0,16,0,0,0,0,0,0,0,0,-123,56,0,8,  // 42999',
+   '9,0,0,-123,56,4,64,9,-101,-74,95,5,0,0,0,16,0,0,0,0,0,0,0,0,-59,79,-128,32,32,0,0,0,0,0,0,0,0,-59,79,-108,32,37,0,0,0,0,0,0,0,0,-59,79,-104,32,38,0,0,0,0,0,0,0,0,-59,  // 43000',
+   '79,-100,32,39,0,0,0,0,0,0,0,0,-91,108,0,8,3,0,0,-91,108,4,96,3,-86,-127,-107,44,127,0,0,24,0,0,0,0,0,0,0,43,0,0,0,0,0,0,0,0,-75,108,0,8,0,0,0,-75,108,4,96,0,-102,-74,95,5,  // 43001',
+   '0,0,0,24,0,0,0,0,0,0,0,45,0,0,0,0,0,0,0,0,-67,108,0,8,5,0,0,-67,108,4,64,5,114,5,54,-2,85,0,0,16,0,0,0,0,0,0,0,0,-51,108,0,8,1,0,0,-51,108,4,96,1,-102,-74,95,5,  // 43002',
-   '0,0,0,1,0,0,0,0,0,0,0,14,0,0,0,64,91,31,0,6,-71,2,5,24,66,66,4,4,8,95,4,73,33,11,15,0,-3,15,0,8,6,0,0,-3,15,4,96,6,-86,33,30,70,127,0,0,24,0,0,0,0,0,0,0,47,  // 42997',
-   '0,0,0,0,0,0,0,0,-107,26,0,8,8,0,0,-107,26,4,64,8,36,-106,100,5,0,0,0,16,0,0,0,0,0,0,0,0,-99,39,0,8,2,0,0,-99,39,4,-64,2,36,-106,100,5,0,0,0,48,0,0,0,0,0,0,0,51,  // 42998',
-   '0,0,0,0,0,0,0,52,0,0,0,0,0,0,0,53,0,0,0,0,0,0,0,54,0,0,0,0,0,0,0,0,-67,49,0,8,7,0,0,-67,49,4,64,7,36,-106,100,5,0,0,0,16,0,0,0,0,0,0,0,0,-123,56,0,8,  // 42999',
-   '9,0,0,-123,56,4,64,9,36,-106,100,5,0,0,0,16,0,0,0,0,0,0,0,0,-59,79,-128,32,32,0,0,0,0,0,0,0,0,-59,79,-108,32,37,0,0,0,0,0,0,0,0,-59,79,-104,32,38,0,0,0,0,0,0,0,0,-59,  // 43000',
-   '79,-100,32,39,0,0,0,0,0,0,0,0,-91,108,0,8,3,0,0,-91,108,4,96,3,-86,33,30,70,127,0,0,24,0,0,0,0,0,0,0,43,0,0,0,0,0,0,0,0,-75,108,0,8,0,0,0,-75,108,4,96,0,36,-106,100,5,  // 43001',
-   '0,0,0,24,0,0,0,0,0,0,0,45,0,0,0,0,0,0,0,0,-67,108,0,8,5,0,0,-67,108,4,64,5,-52,-33,6,76,86,0,0,16,0,0,0,0,0,0,0,0,-51,108,0,8,1,0,0,-51,108,4,96,1,36,-106,100,5,  // 43002',
    '0,0,0,24,0,0,0,0,0,0,0,57,0,0,0,0,0,0,0,11,10,10,10,10',
    '};',
    'static const int v8_snapshot_blob_size = 2752216;',
    'static const uint8_t vm_cache_data[] = {171,6,222,192,82,189,255,151,217,50,0,32,97,100,152,163,213,231,162,201,96,21,0,0,0,0,0,0,0,0,0,0,1,36,81,3,109,1,7,196,96,0,0,0,0,151,2,0,0,1,8,7,33,15,4,4,33,3,112,7,181,1,122,0,  // 0',
    '0,0,0,205,0,0,0,2,4,6,0,179,5,156,36,26,100,22,64,26,76,26,68,26,64,23,220,3,14,0,22,203,2,22,80,26,60,22,112,27,216,3,14,0,22,104,22,203,2,26,124,27,168,9,14,0,22,143,7,26,68,26,76,26,  // 1',

    at Object.<anonymous> (/node/test/parallel/test-snapshot-reproducible.js:47:8)
    at Module._compile (node:internal/modules/cjs/loader:1947:14)
    at Object..js (node:internal/modules/cjs/loader:2087:10)
    at Module.load (node:internal/modules/cjs/loader:1669:32)
    at Module._load (node:internal/modules/cjs/loader:1450:12)
    at wrapModuleLoad (node:internal/modules/cjs/loader:260:19)
    at Module.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:154:5)
    at node:internal/main/run_main_module:33:47 {
  generatedMessage: true,
  code: 'ERR_ASSERTION',
  actual: [ <skipped> ],
  expected: [ <skipped> ],
  operator: 'deepStrictEqual',
  diff: 'simple'
}

Node.js v27.0.0-pre

Reproducible locally with gcc 15.3.0 and 16.1.1.
The byteranges that differ are randomized so the exact bytes are different each time. Everything else seems to be consistent.
Completely disabling ASLR (setting kernel/randomize_va_space to 0) makes the test pass. Conservative ASLR (1) still breaks it.

Not exactly sure when this started (maybe some of v8 upgrades?) nor whether it can be fixed (maybe on v8 side?) nor what else causes this (test passes on CI so i assume there's additional factor to it).