llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang-static-analyzer-1 Author: Balázs Kéri (balazske) <details> <summary>Changes</summary> If variables `stdin`, `stdout`, `stderr` are added to the system memory space, they are invalidated at any call to system (or C library) functions. These variables are not expected to be changed by system functions, therefore should not belong to the system memory space. This change moves these to the "internal memory space" which is not invalidated at system calls (but is at non-system calls). This eliminates some false positives coming from StreamChecker. --- Full diff: https://github.com/llvm/llvm-project/pull/147766.diff 2 Files Affected: - (modified) clang/lib/StaticAnalyzer/Core/MemRegion.cpp (+17-3) - (modified) clang/test/Analysis/stream.c (+42-3) ``````````diff diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp index 63ad567ab7151..4e946f39c1cef 100644 --- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp +++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp @@ -1054,10 +1054,24 @@ const VarRegion *MemRegionManager::getVarRegion(const VarDecl *D, assert(!Ty.isNull()); if (Ty.isConstQualified()) { sReg = getGlobalsRegion(MemRegion::GlobalImmutableSpaceRegionKind); - } else if (Ctx.getSourceManager().isInSystemHeader(D->getLocation())) { - sReg = getGlobalsRegion(MemRegion::GlobalSystemSpaceRegionKind); } else { - sReg = getGlobalsRegion(MemRegion::GlobalInternalSpaceRegionKind); + StringRef N = D->getNameAsString(); + QualType FILETy = D->getASTContext().getFILEType(); + if (!FILETy.isNull()) + FILETy = FILETy.getCanonicalType(); + Ty = Ty.getCanonicalType(); + bool IsStdStreamVar = Ty->isPointerType() && + Ty->getPointeeType() == FILETy && + (N == "stdin" || N == "stdout" || N == "stderr"); + // Pointer value of C standard streams is usually not modified by system + // calls. This means they should not get invalidated at system calls and + // can not belong to the system memory space. + if (Ctx.getSourceManager().isInSystemHeader(D->getLocation()) && + !IsStdStreamVar) { + sReg = getGlobalsRegion(MemRegion::GlobalSystemSpaceRegionKind); + } else { + sReg = getGlobalsRegion(MemRegion::GlobalInternalSpaceRegionKind); + } } // Finally handle static locals. diff --git a/clang/test/Analysis/stream.c b/clang/test/Analysis/stream.c index 758b40cca4931..781c023ea248a 100644 --- a/clang/test/Analysis/stream.c +++ b/clang/test/Analysis/stream.c @@ -519,14 +519,53 @@ void reopen_std_stream(void) { if (!fp) return; stdout = fp; // Let's make them alias. - clang_analyzer_eval(fp == oldStdout); // expected-warning {{UNKNOWN}} - clang_analyzer_eval(fp == stdout); // expected-warning {{TRUE}} no-FALSE - clang_analyzer_eval(oldStdout == stdout); // expected-warning {{UNKNOWN}} + clang_analyzer_eval(fp == oldStdout); // expected-warning {{FALSE}} + clang_analyzer_eval(fp == stdout); // expected-warning {{TRUE}} + clang_analyzer_eval(oldStdout == stdout); // expected-warning {{FALSE}} } void only_success_path_does_not_alias_with_stdout(void) { if (stdout) return; FILE *f = fopen("/tmp/foof", "r"); // no-crash + clang_analyzer_eval(f == 0);// expected-warning {{TRUE}} expected-warning {{FALSE}} if (!f) return; fclose(f); } + +extern void do_something(); + +void test_no_invalidate_at_system_call(int use_std) { + FILE *fd; + char *buf; + + if (use_std) { + fd = stdin; + } else { + if ((fd = fopen("x/y/z", "r")) == NULL) + return; + + clang_analyzer_eval(fd == stdin); // expected-warning{{FALSE}} + buf = (char *)malloc(100); + clang_analyzer_eval(fd == stdin); // expected-warning{{FALSE}} + } + + if (fd != stdin) + fclose(fd); +} + +void test_invalidate_at_non_system_call(int use_std) { + FILE *fd; + + if (use_std) { + fd = stdin; + } else { + if ((fd = fopen("x/y/z", "r")) == NULL) + return; + } + + do_something(); + clang_analyzer_eval(fd == stdin); // expected-warning{{UNKNOWN}} + + if (fd != stdin) + fclose(fd); +} // expected-warning{{Opened stream never closed. Potential resource leak}} `````````` </details> https://github.com/llvm/llvm-project/pull/147766 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
