Author: Ivan Murashko Date: 2023-09-04T18:53:49+01:00 New Revision: d03a7f15f019beb1896872ba9321cfed5f16a05f
URL: https://github.com/llvm/llvm-project/commit/d03a7f15f019beb1896872ba9321cfed5f16a05f DIFF: https://github.com/llvm/llvm-project/commit/d03a7f15f019beb1896872ba9321cfed5f16a05f.diff LOG: [clangd] SIGSEGV at clangd: DiagnosticConsumer Is Used After Free This is a follow-up patch for D148088. The dynamic symbol index (`FileIndex::updatePreamble`) may run in a separate thread, and the `DiagnosticConsumer` that is set up in `buildPreamble` might go out of scope before it is used. This could result in a SIGSEGV when attempting to call any method of the `DiagnosticConsumer` class. The function `buildPreamble` sets up the `DiagnosticConsumer` as follows: ``` ... buildPreamble(...) { ... StoreDiags PreambleDiagnostics; ... llvm::IntrusiveRefCntPtr<DiagnosticsEngine> PreambleDiagsEngine = CompilerInstance::createDiagnostics(&CI.getDiagnosticOpts(), &PreambleDiagnostics, /*ShouldOwnClient=*/false); ... // The call might use the diagnostic consumer in a separate thread PreambleCallback(...) ... } ``` `PreambleDiagnostics` might be out of scope for `buildPreamble` function when we call it inside `PreambleCallback` in a separate thread. The Fix The fix involves replacing the client (DiagnosticConsumer) with an `IgnoringDiagConsumer` instance, which will print messages to the clangd log. Alternatively, we can replace `PreambleDiagnostics` with an object that is owned by `DiagnosticsEngine`. Note There is no corresponding LIT/GTest for this issue, since there is a specific race condition that is difficult to reproduce within a test framework. Test Plan: ``` ninja check-clangd ``` Reviewed By: kadircet, sammccall Differential Revision: https://reviews.llvm.org/D159363 Added: Modified: clang-tools-extra/clangd/Preamble.cpp Removed: ################################################################################ diff --git a/clang-tools-extra/clangd/Preamble.cpp b/clang-tools-extra/clangd/Preamble.cpp index 725e6b1e34fea3..f8fd4327681705 100644 --- a/clang-tools-extra/clangd/Preamble.cpp +++ b/clang-tools-extra/clangd/Preamble.cpp @@ -665,6 +665,10 @@ buildPreamble(PathRef FileName, CompilerInvocation CI, Stats ? TimedFS : StatCacheFS, std::make_shared<PCHContainerOperations>(), StoreInMemory, /*StoragePath=*/"", CapturedInfo); PreambleTimer.stopTimer(); + + // We have to setup DiagnosticConsumer that will be alife + // while preamble callback is executed + PreambleDiagsEngine->setClient(new IgnoringDiagConsumer, true); // Reset references to ref-counted-ptrs before executing the callbacks, to // prevent resetting them concurrently. PreambleDiagsEngine.reset(); @@ -706,6 +710,7 @@ buildPreamble(PathRef FileName, CompilerInvocation CI, // While extending the life of FileMgr and VFS, StatCache should also be // extended. Ctx->setStatCache(Result->StatCache); + PreambleCallback(std::move(*Ctx), Result->Pragmas); } return Result; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
