sea: error instead of SIGSEGV when fuse set without blob

When the postject fuse byte is set but NODE_SEA_BLOB cannot be found,
FindSingleExecutableBlob previously constructed a null string_view and
BlobDeserializer NULL-dereferenced. Exit with a clear error instead.

Fixes: #63466
Signed-off-by: Sankalp Thakur <sankalphimself@gmail.com>

Author: sankalpsthakur

src/node_sea_bin.cc

@@ -20,6 +20,7 @@
 #include "util-inl.h"
 
 #include <algorithm>
+#include <cstdlib>
 #include <memory>
 #include <string>
 #include <string_view>
@@ -40,6 +41,7 @@
 
 namespace node {
 namespace sea {
+using node::ExitCode;
 
 // TODO(joyeecheung): use LIEF to locate it directly.
 std::string_view FindSingleExecutableBlob() {
@@ -57,6 +59,23 @@ std::string_view FindSingleExecutableBlob() {
     const char* blob = static_cast<const char*>(
         postject_find_resource("NODE_SEA_BLOB", &size, nullptr));
 #endif
+    // Fuse set with no (or empty) blob used to NULL-deref in BlobDeserializer.
+    // See https://github.com/nodejs/node/issues/63466.
+    if (blob == nullptr || size == 0) {
+      char exec_path_buf[2 * PATH_MAX];
+      size_t exec_path_len = sizeof(exec_path_buf);
+      const char* path = "this binary";
+      if (uv_exepath(exec_path_buf, &exec_path_len) == 0) {
+        path = exec_path_buf;
+      }
+      FPrintF(stderr,
+              "node: SEA fuse is set but no valid NODE_SEA_BLOB resource "
+              "was found in %s.\n"
+              "The host binary may be missing a PT_NOTE program header "
+              "(run `readelf -lW <binary> | grep NOTE` to check).\n",
+              path);
+      exit(static_cast<int>(ExitCode::kGenericUserError));
+    }
     return {blob, size};
   }();
   per_process::Debug(DebugCategory::SEA,

test/sea/test-single-executable-application-missing-blob.js

@@ -0,0 +1,52 @@
+'use strict';
+
+// Verifies that a host binary with the SEA fuse set but without a
+// NODE_SEA_BLOB resource exits with a clear error instead of SIGSEGV.
+// Regression test for https://github.com/nodejs/node/issues/63466.
+
+require('../common');
+
+const {
+  skipIfSingleExecutableIsNotSupported,
+  signSEA,
+} = require('../common/sea');
+
+skipIfSingleExecutableIsNotSupported();
+
+const tmpdir = require('../common/tmpdir');
+const { copyFileSync, readFileSync, writeFileSync, chmodSync } = require('fs');
+const { join } = require('path');
+const { spawnSyncAndAssert } = require('../common/child_process');
+
+tmpdir.refresh();
+
+const fusedBinary = join(tmpdir.path, process.platform === 'win32' ? 'fused.exe' : 'fused');
+copyFileSync(process.execPath, fusedBinary);
+
+const fuse = Buffer.from('NODE_SEA_FUSE_fce680ab2cc467b6e072b8b5df1996b2');
+const buf = readFileSync(fusedBinary);
+const fuseAt = buf.indexOf(fuse);
+if (fuseAt === -1) {
+  require('../common').skip('SEA fuse sentinel not found in process.execPath');
+}
+
+const fuseValueOffset = fuseAt + fuse.length + 1; // skip ':'
+if (buf[fuseValueOffset] !== 0x30 /* '0' */) {
+  require('../common').skip(`Unexpected SEA fuse value: ${buf[fuseValueOffset]}`);
+}
+
+buf[fuseValueOffset] = 0x31; // '1'
+writeFileSync(fusedBinary, buf);
+chmodSync(fusedBinary, 0o755);
+signSEA(fusedBinary);
+
+spawnSyncAndAssert(
+  fusedBinary,
+  ['--version'],
+  {},
+  {
+    status: 1,
+    signal: null,
+    stderr: /SEA fuse is set but no valid NODE_SEA_BLOB resource was found/,
+  },
+);