ffi: reject fast calls after library close by trivikr · Pull Request #64860 · nodejs/node

trivikr · 2026-07-31T04:10:09Z

Optimized FFI Fast API calls bypass DynamicLibrary::InvokeFunction() and enter the generated trampoline directly. After DynamicLibrary::close() unloads the library, optimized code could call the stale symbol address and crash with SIGSEGV.

This adds a closed-state check to the AArch64 and SysV x64 fast trampolines. The hot path continues to the native symbol when the library is open. The cold path schedules ERR_FFI_LIBRARY_CLOSED and returns without entering the unloaded library.

Assisted-by: codex:gpt-5.6-sol

nodejs-github-bot · 2026-07-31T04:10:14Z

Review requested:

@nodejs/ffi

Optimized Fast API calls bypass InvokeFunction and can jump directly to a symbol after DynamicLibrary::close() unloads its library. Check the function's closed state in the AArch64 and SysV x64 trampolines before entering the target. If the library is closed, schedule ERR_FFI_LIBRARY_CLOSED and return without calling the symbol. Keep the JavaScript guard on platforms without a native trampoline guard and for signatures that already require argument conversion or validation. This keeps raw scalar fast calls close to their original performance on supported platforms. Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com> Assisted-by: codex:gpt-5.6-sol

codecov · 2026-07-31T06:21:14Z

Codecov Report

❌ Patch coverage is 94.73684% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.17%. Comparing base (c8e2a82) to head (14d6323).
⚠️ Report is 39 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ffi/fast.cc	85.71%	1 Missing and 1 partial ⚠️
src/ffi/platforms/arm64.cc	89.47%	0 Missing and 2 partials ⚠️
lib/internal/ffi/fast-api.js	96.96%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #64860      +/-   ##
==========================================
+ Coverage   90.16%   90.17%   +0.01%     
==========================================
  Files         746      746              
  Lines      242760   242847      +87     
  Branches    45765    45768       +3     
==========================================
+ Hits       218875   218987     +112     
+ Misses      15375    15341      -34     
- Partials     8510     8519       +9

Files with missing lines	Coverage Δ
lib/ffi.js	`95.23% <100.00%> (+0.31%)`	⬆️
lib/internal/errors.js	`97.90% <100.00%> (+<0.01%)`	⬆️
src/ffi/fast.h	`100.00% <100.00%> (ø)`
src/node_ffi.cc	`70.45% <100.00%> (-0.18%)`	⬇️
lib/internal/ffi/fast-api.js	`92.32% <96.96%> (+1.25%)`	⬆️
src/ffi/fast.cc	`68.71% <85.71%> (+0.95%)`	⬆️
src/ffi/platforms/arm64.cc	`85.40% <89.47%> (+0.88%)`	⬆️

... and 37 files with indirect coverage changes

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nodejs-github-bot · 2026-07-31T19:16:04Z

CI: https://ci.nodejs.org/job/node-test-pull-request/75341/

mcollina

lgtm

trivikr · 2026-07-31T20:20:19Z

Moved to draft since CI is failing on Linux on ARM

not ok 8 ffi/test-ffi-dynamic-library
  ---
  duration_ms: 509.99000
  severity: crashed
  exitcode: -6
  stack: |-
    (node:3793798) ExperimentalWarning: FFI is an experimental feature and might change at any time
    (Use `node --trace-warnings ...` to show where the warning was created)
    FATAL ERROR: v8::HandleScope::CreateHandle() Cannot create a handle without a HandleScope
    ----- Native stack trace -----
    
     1: 0xc9ccdcdb50cc node::DumpNativeBacktrace(_IO_FILE*) [out/Debug/node]
     2: 0xc9ccdcf2bad8 node::OnFatalError(char const*, char const*) [out/Debug/node]
     3: 0xc9ccdd3bb228  [out/Debug/node]
     4: 0xc9ccdd7e04e8  [out/Debug/node]
     5: 0xc9ccdd3b1794  [out/Debug/node]
     6: 0xc9ccddf78f80  [out/Debug/node]
     7: 0xc9ccdd878fc8  [out/Debug/node]
     8: 0xc9ccdd3f50f4 v8::String::NewFromOneByte(v8::Isolate*, unsigned char const*, v8::NewStringType, int) [out/Debug/node]
     9: 0xc9ccdccfd20c node::OneByteString(v8::Isolate*, char const*, int, v8::NewStringType) [out/Debug/node]
    10: 0xc9ccdcd2cd20 v8::Local<v8::String> node::FIXED_ONE_BYTE_STRING<23ul>(v8::Isolate*, char const (&) [23ul]) requires ((23ul)>(0)) [out/Debug/node]
    11: 0xc9ccdd2104b8 v8::Local<v8::Object> node::ERR_FFI_LIBRARY_CLOSED<>(v8::Isolate*, std::basic_string_view<char, std::char_traits<char> >) [out/Debug/node]
    12: 0xc9ccdd21043c node::THROW_ERR_FFI_LIBRARY_CLOSED(v8::Isolate*) [out/Debug/node]
    13: 0xc9ccdd221ef0 node_ffi_fast_library_closed [out/Debug/node]
    14: 0xebea4cb1b044 
    FATAL ERROR: v8::HandleScope::CreateHandle() Cannot create a handle without a HandleScope
    ----- Native stack trace -----
    
     1: 0xc9ccdcdb50cc node::DumpNativeBacktrace(_IO_FILE*) [out/Debug/node]
     2: 0xc9ccdcf2bad8 node::OnFatalError(char const*, char const*) [out/Debug/node]
     3: 0xc9ccdd3bb228  [out/Debug/node]
     4: 0xc9ccdd7e04e8  [out/Debug/node]
     5: 0xc9ccdd3bc518 v8::EscapableHandleScopeBase::EscapableHandleScopeBase(v8::Isolate*) [out/Debug/node]
     6: 0xc9ccdccf9a04 v8::EscapableHandleScope::EscapableHandleScope(v8::Isolate*) [out/Debug/node]
     7: 0xc9ccdcf2a08c node::GetCurrentStackTrace(v8::Isolate*, int) [out/Debug/node]
     8: 0xc9ccdcdb51f0 node::DumpJavaScriptBacktrace(_IO_FILE*) [out/Debug/node]
     9: 0xc9ccdcf2bae4 node::OnFatalError(char const*, char const*) [out/Debug/node]
    10: 0xc9ccdd3bb228  [out/Debug/node]
    11: 0xc9ccdd7e04e8  [out/Debug/node]
    12: 0xc9ccdd3b1794  [out/Debug/node]
    13: 0xc9ccddf78f80  [out/Debug/node]
    14: 0xc9ccdd878fc8  [out/Debug/node]
    15: 0xc9ccdd3f50f4 v8::String::NewFromOneByte(v8::Isolate*, unsigned char const*, v8::NewStringType, int) [out/Debug/node]
    16: 0xc9ccdccfd20c node::OneByteString(v8::Isolate*, char const*, int, v8::NewStringType) [out/Debug/node]
    17: 0xc9ccdcd2cd20 v8::Local<v8::String> node::FIXED_ONE_BYTE_STRING<23ul>(v8::Isolate*, char const (&) [23ul]) requires ((23ul)>(0)) [out/Debug/node]
    18: 0xc9ccdd2104b8 v8::Local<v8::Object> node::ERR_FFI_LIBRARY_CLOSED<>(v8::Isolate*, std::basic_string_view<char, std::char_traits<char> >) [out/Debug/node]
    19: 0xc9ccdd21043c node::THROW_ERR_FFI_LIBRARY_CLOSED(v8::Isolate*) [out/Debug/node]
    20: 0xc9ccdd221ef0 node_ffi_fast_library_closed [out/Debug/node]
    21: 0xebea4cb1b044 
  ...

CI: https://ci.nodejs.org/job/node-test-commit-arm-debug/24671/

Fast API calls run without an entered HandleScope, and the generated trampolines call node_ffi_fast_library_closed() directly. Constructing ERR_FFI_LIBRARY_CLOSED allocates handles, which aborted debug builds with "Cannot create a handle without a HandleScope". Open a HandleScope in the helper before throwing. The scheduled exception is stored on the isolate, so it outlives the scope. Apply the same fix to node_ffi_fast_buffer_data(), which had the same latent bug on its throw path.

trivikr · 2026-07-31T21:49:29Z

CI to test fixup: https://ci.nodejs.org/job/node-test-commit-arm-debug/24674/

nodejs-github-bot · 2026-07-31T21:52:20Z

CI: https://ci.nodejs.org/job/node-test-pull-request/75348/

nodejs-github-bot · 2026-08-02T14:54:44Z

Landed in c55eb4a

Optimized Fast API calls bypass InvokeFunction and can jump directly to a symbol after DynamicLibrary::close() unloads its library. Check the function's closed state in the AArch64 and SysV x64 trampolines before entering the target. If the library is closed, schedule ERR_FFI_LIBRARY_CLOSED and return without calling the symbol. Keep the JavaScript guard on platforms without a native trampoline guard and for signatures that already require argument conversion or validation. This keeps raw scalar fast calls close to their original performance on supported platforms. Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com> Assisted-by: codex:gpt-5.6-sol PR-URL: #64860 Fixes: #64854 Reviewed-By: Paolo Insogna <paolo@cowtech.it> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. lib / src Issues and PRs related to general changes in the lib or src directory. needs-ci PRs that need a full CI run. labels Jul 31, 2026

trivikr force-pushed the ffi-closed-lib-cal-sigsegv-3 branch from 8e91308 to 3b1b100 Compare July 31, 2026 04:27

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mcollina approved these changes Jul 31, 2026

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trivikr marked this pull request as draft July 31, 2026 20:20

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trivikr added the ffi Issues and PRs related to experimental Foreign Function Interface support. label Aug 1, 2026

trivikr requested a review from ShogunPanda August 2, 2026 02:48

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nodejs-github-bot merged commit c55eb4a into nodejs:main Aug 2, 2026
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ffi: reject fast calls after library close - #64860

ffi: reject fast calls after library close#64860
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