Skip to content

Partial fix for #14859 FN bufferAccessOutOfBounds (memset on std::vector) #8690

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
chrchr-github wants to merge 4 commits into
base: main
Choose a base branch
from
+28 −8
Open

Partial fix for #14859 FN bufferAccessOutOfBounds (memset on std::vector) #8690

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
38af593
Update testbufferoverrun.cpp
chrchr-github Jul 3, 2026
fe77659
Update checkbufferoverrun.h
chrchr-github Jul 3, 2026
6525abf
Update checkbufferoverrun.cpp
chrchr-github Jul 3, 2026
cb7a72d
Update checkbufferoverrun.cpp
chrchr-github Jul 3, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
28 changes: 21 additions & 7 deletions lib/checkbufferoverrun.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,10 @@ static const CWE CWE_BUFFER_OVERRUN(788U); // Access of Memory Location After
static const ValueFlow::Value *getBufferSizeValue(const Token *tok)
{
const std::list<ValueFlow::Value> &tokenValues = tok->values();
const auto it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), std::mem_fn(&ValueFlow::Value::isBufferSizeValue));
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));
return it == tokenValues.cend() ? nullptr : &*it;
}

Expand Down Expand Up @@ -552,7 +555,7 @@ void CheckBufferOverrunImpl::pointerArithmeticError(const Token *tok, const Toke

//---------------------------------------------------------------------------

ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok) const
ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok, const Settings& settings) const
{
if (!bufTok->valueType())
return ValueFlow::Value(-1);
Expand All @@ -569,9 +572,20 @@ ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok) cons
const Variable *var = bufTok->variable();

if (!var || var->dimensions().empty()) {
const ValueFlow::Value *value = getBufferSizeValue(bufTok);
if (value)
return *value;
if (const ValueFlow::Value *value = getBufferSizeValue(bufTok)) {
if (value->isBufferSizeValue())
return *value;
if (value->isContainerSizeValue() && bufTok->valueType() && bufTok->valueType()->container) {
const ValueType vtElement = ValueType::parseDecl(bufTok->valueType()->containerTypeToken, settings);
const size_t elementSize = vtElement.getSizeOf(settings, ValueType::Accuracy::ExactOrZero, ValueType::SizeOf::Pointer);
if (elementSize > 0) {
ValueFlow::Value bufSizeVal;
bufSizeVal.valueType = ValueFlow::Value::ValueType::BUFFER_SIZE;
bufSizeVal.intvalue = value->intvalue * elementSize;
return bufSizeVal;
}
}
}
}

if (!var || var->isPointer() || (astIsContainer(bufTok) && var->getTypeName() != "std::array"))
Expand Down Expand Up @@ -671,7 +685,7 @@ void CheckBufferOverrunImpl::bufferOverflow()
if (argtok->valueType() && argtok->valueType()->pointer == 0)
continue;
// TODO: strcpy(buf+10, "hello");
const ValueFlow::Value bufferSize = getBufferSize(argtok);
const ValueFlow::Value bufferSize = getBufferSize(argtok, mSettings);
if (bufferSize.intvalue <= 0)
continue;
// buffer size == 1 => do not warn for dynamic memory
Expand Down Expand Up @@ -782,7 +796,7 @@ void CheckBufferOverrunImpl::stringNotZeroTerminated()
const Token *sizeToken = args[2];
if (!sizeToken->hasKnownIntValue())
continue;
const ValueFlow::Value &bufferSize = getBufferSize(args[0]);
const ValueFlow::Value &bufferSize = getBufferSize(args[0], mSettings);
if (bufferSize.intvalue < 0 || sizeToken->getKnownIntValue() < bufferSize.intvalue)
continue;
if (Token::simpleMatch(args[1], "(") && Token::simpleMatch(args[1]->astOperand1(), ". c_str") && args[1]->astOperand1()->astOperand1()) {
Expand Down
2 changes: 1 addition & 1 deletion lib/checkbufferoverrun.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -129,7 +129,7 @@ class CPPCHECKLIB CheckBufferOverrunImpl : public CheckImpl
void objectIndex();
void objectIndexError(const Token *tok, const ValueFlow::Value *v, bool known);

ValueFlow::Value getBufferSize(const Token *bufTok) const;
ValueFlow::Value getBufferSize(const Token *bufTok, const Settings& settings) const;

// CTU
static bool isCtuUnsafeBufferUsage(const Settings &settings, const Token *argtok, CTU::FileInfo::Value *offset, int type);
Expand Down
6 changes: 6 additions & 0 deletions test/testbufferoverrun.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3545,6 +3545,12 @@ class TestBufferOverrun : public TestFixture {
" std::memset(&buf[0], 0, 25);\n"
"}\n");
ASSERT_EQUALS("", errout_str());

check("void f() {\n" // #14859
" std::vector<char> buf(25);\n"
" std::memset(&buf[0], 0, 26);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3:17]: (error) Buffer is accessed out of bounds: &buf[0] [bufferAccessOutOfBounds]\n", errout_str());
}

void buffer_overrun_errorpath() {
Expand Down
Loading