From 038771a25a61bab8db3dea04594ca77faaf67dea Mon Sep 17 00:00:00 2001 From: Max Moroz Date: Fri, 13 Jul 2018 22:49:06 +0000 Subject: [PATCH] [UBSan] Followup for silence_unsigned_overflow flag to handle negate overflows. Summary: That flag has been introduced in https://reviews.llvm.org/D48660 for suppressing UIO error messages in an efficient way. The main motivation is to be able to use UIO checks in builds used for fuzzing as it might provide an interesting signal to a fuzzing engine such as libFuzzer. See https://github.com/google/oss-fuzz/issues/910 for more information. Reviewers: morehouse, kcc Reviewed By: morehouse Subscribers: kubamracek, delcypher, #sanitizers, llvm-commits Differential Revision: https://reviews.llvm.org/D49324 llvm-svn: 337068 --- compiler-rt/lib/ubsan/ubsan_handlers.cc | 3 +++ compiler-rt/test/ubsan/TestCases/Integer/negate-overflow.cpp | 4 +++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/compiler-rt/lib/ubsan/ubsan_handlers.cc b/compiler-rt/lib/ubsan/ubsan_handlers.cc index b48862a9d6dd..49c6bcacbe27 100644 --- a/compiler-rt/lib/ubsan/ubsan_handlers.cc +++ b/compiler-rt/lib/ubsan/ubsan_handlers.cc @@ -156,6 +156,9 @@ static void handleNegateOverflowImpl(OverflowData *Data, ValueHandle OldVal, if (ignoreReport(Loc, Opts, ET)) return; + if (!IsSigned && flags()->silence_unsigned_overflow) + return; + ScopedReport R(Opts, Loc, ET); if (IsSigned) diff --git a/compiler-rt/test/ubsan/TestCases/Integer/negate-overflow.cpp b/compiler-rt/test/ubsan/TestCases/Integer/negate-overflow.cpp index 72438d3fba7f..5e36b9db657f 100644 --- a/compiler-rt/test/ubsan/TestCases/Integer/negate-overflow.cpp +++ b/compiler-rt/test/ubsan/TestCases/Integer/negate-overflow.cpp @@ -1,10 +1,12 @@ // RUN: %clangxx -fsanitize=signed-integer-overflow %s -o %t1 && %run %t1 2>&1 | FileCheck %s --check-prefix=CHECKS // RUN: %clangxx -fsanitize=unsigned-integer-overflow %s -o %t2 && %run %t2 2>&1 | FileCheck %s --check-prefix=CHECKU +// RUN: %clangxx -fsanitize=unsigned-integer-overflow %s -o %t2 && %env_ubsan_opts=silence_unsigned_overflow=1 %run %t2 2>&1 | FileCheck %s --check-prefix=CHECKU-SILENT --allow-empty int main() { // CHECKS-NOT: runtime error - // CHECKU: negate-overflow.cpp:[[@LINE+2]]:3: runtime error: negation of 2147483648 cannot be represented in type 'unsigned int' + // CHECKU: negate-overflow.cpp:[[@LINE+3]]:3: runtime error: negation of 2147483648 cannot be represented in type 'unsigned int' // CHECKU-NOT: cast to an unsigned + // CHECKU-SILENT-NOT: runtime error -unsigned(-0x7fffffff - 1); // ok // CHECKS: negate-overflow.cpp:[[@LINE+2]]:3: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself // CHECKU-NOT: runtime error