[PATCH] D48660: [UBSan] Add silence_unsigned_overflow flag.

[Matt Morehouse via Phabricator via llvm-commits]

morehouse created this revision.
morehouse added a reviewer: kcc.
Herald added a subscriber: kubamracek.

Setting UBSAN_OPTIONS=silence_unsigned_overflow=1 will silence all UIO
reports.  This feature, combined with
-fsanitize-recover=unsigned-integer-overflow, is useful for providing
fuzzing signal without the excessive log output.

Helps with https://github.com/google/oss-fuzz/issues/910.


https://reviews.llvm.org/D48660

Files:
  compiler-rt/lib/ubsan/ubsan_flags.inc
  compiler-rt/lib/ubsan/ubsan_handlers.cc
  compiler-rt/test/ubsan/TestCases/Integer/no-recover.cpp


Index: compiler-rt/test/ubsan/TestCases/Integer/no-recover.cpp
===================================================================
--- compiler-rt/test/ubsan/TestCases/Integer/no-recover.cpp
+++ compiler-rt/test/ubsan/TestCases/Integer/no-recover.cpp
@@ -1,8 +1,10 @@
 // RUN: %clangxx -fsanitize=unsigned-integer-overflow %s -o %t && %run %t 2>&1 | FileCheck %s --check-prefix=RECOVER
 // RUN: %clangxx -fsanitize=unsigned-integer-overflow -fno-sanitize-recover=all -fsanitize-recover=unsigned-integer-overflow %s -o %t && %run %t 2>&1 | FileCheck %s --check-prefix=RECOVER
+// RUN: %env_ubsan_opts=silence_unsigned_overflow=1 %run %t 2>&1 | FileCheck %s --check-prefix=SILENT-RECOVER
 // RUN: %clangxx -fsanitize=unsigned-integer-overflow -fno-sanitize-recover=unsigned-integer-overflow %s -o %t && not %run %t 2>&1 | FileCheck %s --check-prefix=ABORT
 
 #include <stdint.h>
+#include <stdio.h>
 
 int main() {
   // These promote to 'int'.
@@ -18,5 +20,8 @@
 
   (void)(uint64_t(10000000000000000000ull) + uint64_t(9000000000000000000ull));
   // RECOVER: 10000000000000000000 + 9000000000000000000 cannot be represented in type 'unsigned {{long( long)?}}'
+  // SILENT-RECOVER-NOT: runtime error
   // ABORT-NOT: runtime error
+
+  printf("%\n");  // Provide some output to search for SILENT-RECOVER case.
 }
Index: compiler-rt/lib/ubsan/ubsan_handlers.cc
===================================================================
--- compiler-rt/lib/ubsan/ubsan_handlers.cc
+++ compiler-rt/lib/ubsan/ubsan_handlers.cc
@@ -15,6 +15,7 @@
 #if CAN_SANITIZE_UB
 #include "ubsan_handlers.h"
 #include "ubsan_diag.h"
+#include "ubsan_flags.h"
 #include "ubsan_monitor.h"
 
 #include "sanitizer_common/sanitizer_common.h"
@@ -118,6 +119,9 @@
   if (ignoreReport(Loc, Opts, ET))
     return;
 
+  if (!IsSigned && flags()->silence_unsigned_overflow)
+    return;
+
   ScopedReport R(Opts, Loc, ET);
 
   Diag(Loc, DL_Error, ET, "%0 integer overflow: "
Index: compiler-rt/lib/ubsan/ubsan_flags.inc
===================================================================
--- compiler-rt/lib/ubsan/ubsan_flags.inc
+++ compiler-rt/lib/ubsan/ubsan_flags.inc
@@ -24,3 +24,6 @@
 UBSAN_FLAG(const char *, suppressions, "", "Suppressions file name.")
 UBSAN_FLAG(bool, report_error_type, false,
         "Print specific error type instead of 'undefined-behavior' in summary.")
+UBSAN_FLAG(bool, silence_unsigned_overflow, false,
+	"Do not print error reports for unsigned integer overflow. "
+	"Used to provide fuzzing signal without blowing up logs.")


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