Author: Pavel Skripkin Date: 2024-08-15T11:42:27+02:00 New Revision: 5e95571a90b1ec193b735b7312c5c2559d7ee5ea
URL: https://github.com/llvm/llvm-project/commit/5e95571a90b1ec193b735b7312c5c2559d7ee5ea DIFF: https://github.com/llvm/llvm-project/commit/5e95571a90b1ec193b735b7312c5c2559d7ee5ea.diff LOG: [analyzer] Do not reason about locations passed as inline asm input (#103714) If pointer is passed as input operand for inline assembly, it's possible that asm block will change memory behind this pointer. So if pointer is passed inside inline asm block, it's better to not guess and assume memory has unknown state. Without such change, we observed a lot of FP with hand-written `memcpy` and friends. Added: Modified: clang/lib/StaticAnalyzer/Core/ExprEngine.cpp clang/test/Analysis/asm.cpp Removed: ################################################################################ diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp index 686310d38ebd58..493914f88ba9a5 100644 --- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp +++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp @@ -3807,6 +3807,14 @@ void ExprEngine::VisitGCCAsmStmt(const GCCAsmStmt *A, ExplodedNode *Pred, state = state->bindLoc(*LV, UnknownVal(), Pred->getLocationContext()); } + // Do not reason about locations passed inside inline assembly. + for (const Expr *I : A->inputs()) { + SVal X = state->getSVal(I, Pred->getLocationContext()); + + if (std::optional<Loc> LV = X.getAs<Loc>()) + state = state->bindLoc(*LV, UnknownVal(), Pred->getLocationContext()); + } + Bldr.generateNode(A, Pred, state); } diff --git a/clang/test/Analysis/asm.cpp b/clang/test/Analysis/asm.cpp index 1180063502168f..3181aea870c8aa 100644 --- a/clang/test/Analysis/asm.cpp +++ b/clang/test/Analysis/asm.cpp @@ -1,4 +1,5 @@ -// RUN: %clang_analyze_cc1 -analyzer-checker debug.ExprInspection -fheinous-gnu-extensions -w %s -verify +// RUN: %clang_analyze_cc1 -triple=x86_64-unknown-unknown \ +// RUN: -analyzer-checker debug.ExprInspection,core -fheinous-gnu-extensions -w %s -verify int clang_analyzer_eval(int); @@ -10,3 +11,32 @@ void testRValueOutput() { clang_analyzer_eval(global == 1); // expected-warning{{UNKNOWN}} clang_analyzer_eval(ref == 1); // expected-warning{{UNKNOWN}} } + +void *MyMemcpy(void *d, const void *s, const int n) { + asm volatile ( + "cld\n rep movsb\n" + :: "S" (s), "D" (d), "c" (n) : "memory" + ); + return d; +} + +void testInlineAsmMemcpy(void) +{ + int a, b = 10, c; + MyMemcpy(&a, &b, sizeof(b)); + c = a; // no-warning +} + +void testInlineAsmMemcpyArray(void) +{ + int a[10], b[10] = {}, c; + MyMemcpy(&a, &b, sizeof(b)); + c = a[8]; // no-warning +} + +void testInlineAsmMemcpyUninit(void) +{ + int a[10], b[10] = {}, c; + MyMemcpy(&a[1], &b[1], sizeof(b) - sizeof(b[1])); + c = a[0]; // expected-warning{{Assigned value is garbage or undefined}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
