[scudo] simplify flag parser out of bounds logic

[fmayer]

almost NFC, just that now we accept INT_MIN and INT_MAX

as discussed in https://r.android.com/2831100, but I didn't add the *ValueEnd != Value check because I want to keep this change behaviour-keeping.

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Florian Mayer (fmayer)

Changes

almost NFC, just that now we accept INT_MIN and INT_MAX

as discussed in https://r.android.com/2831100, but I didn't add the *ValueEnd != Value check because I want to keep this change behaviour-keeping.

---

Full diff: https://github.com/llvm/llvm-project/pull/72371.diff

1 Files Affected:

• (modified) compiler-rt/lib/scudo/standalone/flags_parser.cpp (+9-9)

diff --git a/compiler-rt/lib/scudo/standalone/flags_parser.cpp b/compiler-rt/lib/scudo/standalone/flags_parser.cpp
index 6f9b23ea90e23cc..3d8c6f3789b4ccb 100644
--- a/compiler-rt/lib/scudo/standalone/flags_parser.cpp
+++ b/compiler-rt/lib/scudo/standalone/flags_parser.cpp
@@ -10,6 +10,7 @@
 #include "common.h"
 #include "report.h"
 
+#include <errno.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ -143,19 +144,18 @@ bool FlagParser::runHandler(const char *Name, const char *Value,
       break;
     case FlagType::FT_int:
       char *ValueEnd;
+      errno = 0;
       long V = strtol(Value, &ValueEnd, 10);
-      // strtol returns LONG_MAX on overflow and LONG_MIN on underflow.
-      // This is why we compare-equal here (and lose INT_MIN and INT_MAX as a
-      // value, but that's okay)
-      if (V >= INT_MAX || V <= INT_MIN) {
+      if (errno != 0 ||                 // strtol failed (over or underflow)
+          V > INT_MAX || V < INT_MIN || // overflows integer
+          // contains unexpected characters
+          (*ValueEnd != '"' && *ValueEnd != '\'' &&
+           !isSeparatorOrNull(*ValueEnd))) {
         reportInvalidFlag("int", Value);
-        return false;
+        break;
       }
       *reinterpret_cast<int *>(Flags[I].Var) = static_cast<int>(V);
-      Ok =
-          *ValueEnd == '"' || *ValueEnd == '\'' || isSeparatorOrNull(*ValueEnd);
-      if (!Ok)
-        reportInvalidFlag("int", Value);
+      Ok = true;
       break;
     }
     return Ok;