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Fix #14960 Inconsistent bufferAccessOutOfBounds (possible values) #8779

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Fix #14960 Inconsistent bufferAccessOutOfBounds (possible values) #8779

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0b19a52
Update checkbufferoverrun.cpp
chrchr-github Jul 29, 2026
88a9426
Update testbufferoverrun.cpp
chrchr-github Jul 29, 2026
31b88ba
Update checkbufferoverrun.cpp
chrchr-github Jul 29, 2026
13bc2fa
Allow possible values
web-flow Aug 4, 2026
d9b785a
Format
web-flow Aug 4, 2026
cc85761
Partial fix for #14960
web-flow Aug 5, 2026
7e3ba00
Fix
web-flow Aug 5, 2026
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40 changes: 28 additions & 12 deletions lib/checkbufferoverrun.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,9 @@ static const ValueFlow::Value *getBufferSizeValue(const Token *tok)
auto it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), std::mem_fn(&ValueFlow::Value::isBufferSizeValue));
if (it != tokenValues.cend())
return &*it;
it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), std::mem_fn(&ValueFlow::Value::isContainerSizeValue));
it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), [](const ValueFlow::Value& v) {
return v.isContainerSizeValue() && !v.isImpossible();
});
return it == tokenValues.cend() ? nullptr : &*it;
}

Expand Down Expand Up @@ -588,6 +590,8 @@ ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok, cons
ValueFlow::Value bufSizeVal;
bufSizeVal.valueType = ValueFlow::Value::ValueType::BUFFER_SIZE;
bufSizeVal.intvalue = value->intvalue * elementSize;
bufSizeVal.valueKind = value->valueKind;
bufSizeVal.errorPath = value->errorPath;
return bufSizeVal;
}
}
Expand Down Expand Up @@ -616,28 +620,37 @@ ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok, cons
}
//---------------------------------------------------------------------------

static bool checkBufferSize(const Token *ftok, const Library::ArgumentChecks::MinSize &minsize, const std::vector<const Token *> &args, const MathLib::bigint bufferSize, const Settings &settings, const Tokenizer* tokenizer)
static bool checkBufferSize(const Token *ftok, const Library::ArgumentChecks::MinSize &minsize, const std::vector<const Token *> &args, ValueFlow::Value& bufferSize, const Settings &settings, const Tokenizer* tokenizer)
{
const Token * const arg = (minsize.arg > 0 && minsize.arg - 1 < args.size()) ? args[minsize.arg - 1] : nullptr;
const Token * const arg2 = (minsize.arg2 > 0 && minsize.arg2 - 1 < args.size()) ? args[minsize.arg2 - 1] : nullptr;

switch (minsize.type) {
case Library::ArgumentChecks::MinSize::Type::STRLEN:
if (settings.library.isargformatstr(ftok, minsize.arg)) {
return getMinFormatStringOutputLength(args, minsize.arg, settings) < bufferSize;
return getMinFormatStringOutputLength(args, minsize.arg, settings) < bufferSize.intvalue;
} else if (arg) {
const Token *strtoken = arg->getValueTokenMaxStrLength();
if (strtoken)
return Token::getStrLength(strtoken) < bufferSize;
return Token::getStrLength(strtoken) < bufferSize.intvalue;
}
break;
case Library::ArgumentChecks::MinSize::Type::ARGVALUE: {
if (arg && arg->hasKnownIntValue()) {
MathLib::bigint myMinsize = arg->getKnownIntValue();
if (arg) {
const ValueFlow::Value* argVal = arg->hasKnownIntValue() ? &arg->values().front() : arg->getMaxValue(true);
if (!argVal)
break;
MathLib::bigint myMinsize = argVal->intvalue;
const int baseSize = tokenizer->sizeOfType(minsize.baseType);
if (baseSize != 0)
myMinsize *= baseSize;
return myMinsize <= bufferSize;
const bool ok = myMinsize <= bufferSize.intvalue;
if (!ok) {
bufferSize.errorPath.insert(bufferSize.errorPath.end(), argVal->errorPath.begin(), argVal->errorPath.end());
if (!bufferSize.condition)
bufferSize.condition = argVal->condition;
}
return ok;
}
break;
}
Expand All @@ -646,14 +659,14 @@ static bool checkBufferSize(const Token *ftok, const Library::ArgumentChecks::Mi
break;
case Library::ArgumentChecks::MinSize::Type::MUL:
if (arg && arg2 && arg->hasKnownIntValue() && arg2->hasKnownIntValue())
return (arg->getKnownIntValue() * arg2->getKnownIntValue()) <= bufferSize;
return (arg->getKnownIntValue() * arg2->getKnownIntValue()) <= bufferSize.intvalue;
break;
case Library::ArgumentChecks::MinSize::Type::VALUE: {
MathLib::bigint myMinsize = minsize.value;
const int baseSize = tokenizer->sizeOfType(minsize.baseType);
if (baseSize != 0)
myMinsize *= baseSize;
return myMinsize <= bufferSize;
return myMinsize <= bufferSize.intvalue;
}
case Library::ArgumentChecks::MinSize::Type::NONE:
break;
Expand Down Expand Up @@ -691,7 +704,7 @@ void CheckBufferOverrunImpl::bufferOverflow()
if (argtok->valueType() && argtok->valueType()->pointer == 0)
continue;
// TODO: strcpy(buf+10, "hello");
const ValueFlow::Value bufferSize = getBufferSize(argtok, mSettings);
ValueFlow::Value bufferSize = getBufferSize(argtok, mSettings);
if (bufferSize.intvalue <= 0)
continue;
// buffer size == 1 => do not warn for dynamic memory
Expand All @@ -710,7 +723,7 @@ void CheckBufferOverrunImpl::bufferOverflow()
}
}
const bool error = std::none_of(minsizes->begin(), minsizes->end(), [&](const Library::ArgumentChecks::MinSize &minsize) {
return checkBufferSize(tok, minsize, args, bufferSize.intvalue, mSettings, mTokenizer);
return checkBufferSize(tok, minsize, args, bufferSize, mSettings, mTokenizer);
});
if (error)
bufferOverflowError(args[argnr], &bufferSize, Certainty::normal);
Expand All @@ -721,7 +734,10 @@ void CheckBufferOverrunImpl::bufferOverflow()

void CheckBufferOverrunImpl::bufferOverflowError(const Token *tok, const ValueFlow::Value *value, Certainty certainty)
{
reportError(getErrorPath(tok, value, "Buffer overrun"), Severity::error, "bufferAccessOutOfBounds", "Buffer is accessed out of bounds: " + (tok ? getRealBufferTok(tok)->expressionString() : "buf"), CWE_BUFFER_OVERRUN, certainty);
const auto errorPath = getErrorPath(tok, value, "Buffer overrun");
const auto severity = !value || (value->isKnown() && !value->condition) ? Severity::error : Severity::warning;
const std::string msg = "Buffer is accessed out of bounds: " + (tok ? getRealBufferTok(tok)->expressionString() : "buf");
reportError(errorPath, severity, "bufferAccessOutOfBounds", msg, CWE_BUFFER_OVERRUN, certainty);
}

//---------------------------------------------------------------------------
Expand Down
34 changes: 34 additions & 0 deletions test/testbufferoverrun.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3564,6 +3564,14 @@ class TestBufferOverrun : public TestFixture {
" memset(&a[i], 0, sizeof(a));\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4:16]: (error) Buffer is accessed out of bounds: &a[i] [bufferAccessOutOfBounds]\n", errout_str());

check("void f(const std::vector<uint8_t>& s) {\n" // #14948
" if (s.size() < 4)\n"
" return;\n"
" uint32_t u = 0;\n"
" std::memcpy(&u, &s[0], sizeof(u));\n"
"}\n");
ASSERT_EQUALS("", errout_str());
}

void buffer_overrun_errorpath() {
Expand All @@ -3578,6 +3586,32 @@ class TestBufferOverrun : public TestFixture {
ASSERT_EQUALS("[test.cpp:3:12]: error: Buffer is accessed out of bounds: p [bufferAccessOutOfBounds]\n"
"[test.cpp:2:13]: note: Assign p, buffer with size 10\n"
"[test.cpp:3:12]: note: Buffer overrun\n", errout_str());

check("void f(const std::vector<uint8_t>& s) {\n"
" if (s.size() == 2) {}\n"
" uint32_t u = 0;\n"
" std::memcpy(&u, &s[0], sizeof(u));\n"
"}\n", s);
ASSERT_EQUALS("[test.cpp:4:21]: warning: Buffer is accessed out of bounds: &s[0] [bufferAccessOutOfBounds]\n"
"[test.cpp:2:18]: note: Assuming that condition 's.size()==2' is not redundant\n"
"[test.cpp:4:21]: note: Buffer overrun\n", errout_str());

check("void f(int i) {\n" // #14960
" int a[1];\n"
" if (i != 2) return;\n"
" memset(a, 0, i * sizeof(int));\n"
"}"
"void g(int i) {\n"
" int a[1];\n"
" if (i != 2) {}\n"
" memset(a, 0, i * sizeof(int));\n"
"}", s);
ASSERT_EQUALS("[test.cpp:4:12]: warning: Buffer is accessed out of bounds: a [bufferAccessOutOfBounds]\n"
"[test.cpp:3:11]: note: Assuming that condition 'i!=2' is not redundant\n"
"[test.cpp:4:12]: note: Buffer overrun\n"
"[test.cpp:8:12]: warning: Buffer is accessed out of bounds: a [bufferAccessOutOfBounds]\n"
"[test.cpp:7:11]: note: Assuming that condition 'i!=2' is not redundant\n"
"[test.cpp:8:12]: note: Buffer overrun\n", errout_str());
}

void buffer_overrun_bailoutIfSwitch() {
Expand Down
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