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[os_log] Fix a CodeGen crash that occurs when arguments of struct, class, or complex types are passed to _builtin_os_log_format #158744

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Merged
merged 3 commits into from
Sep 23, 2025
Merged

[os_log] Fix a CodeGen crash that occurs when arguments of struct, class, or complex types are passed to _builtin_os_log_format #158744

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2100dca
[os_log] Fix a CodeGen crash that occurs when arguments of struct,
ahatanak Sep 5, 2025
b00413b
Merge branch 'main' into fix-os-log-crash
ahatanak Sep 23, 2025
d82fed8
Error out if struct or complex type arguments are passed
ahatanak Sep 23, 2025
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48 changes: 32 additions & 16 deletions clang/lib/AST/OSLog.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -70,22 +70,31 @@ class OSLogFormatStringHandler
bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
const char *StartSpecifier, unsigned SpecifierLen,
const TargetInfo &) override {
// Set the argument expression. Arguments of struct/class/complex types are
// ignored.
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Is there any reason we can't diagnose this as an error? A priori, it seems no one can be doing this right now because it crashes clang. The layout is going to be super broken if we skip arguments.

auto CheckAndSetArgExpr = [&](unsigned Idx, auto &ArgE) {
const Expr *E = Args[Idx];
if (E && (E->getType()->isRecordType() || E->getType()->isComplexType()))
return false;
ArgE = E;
return true;
};

if (!FS.consumesDataArgument() &&
FS.getConversionSpecifier().getKind() !=
clang::analyze_format_string::ConversionSpecifier::PrintErrno)
return true;

ArgsData.emplace_back();
ArgData ArgD;
unsigned ArgIndex = FS.getArgIndex();
if (ArgIndex < Args.size())
ArgsData.back().E = Args[ArgIndex];
if (!CheckAndSetArgExpr(ArgIndex, ArgD.E))
return true;

// First get the Kind
ArgsData.back().Kind = getKind(FS.getConversionSpecifier().getKind());
if (ArgsData.back().Kind != OSLogBufferItem::ErrnoKind &&
!ArgsData.back().E) {
ArgD.Kind = getKind(FS.getConversionSpecifier().getKind());
if (ArgD.Kind != OSLogBufferItem::ErrnoKind && !ArgD.E) {
// missing argument
ArgsData.pop_back();
return false;
}

Expand All @@ -97,10 +106,11 @@ class OSLogFormatStringHandler
case clang::analyze_format_string::OptionalAmount::NotSpecified: // "%s"
break;
case clang::analyze_format_string::OptionalAmount::Constant: // "%.16s"
ArgsData.back().Size = precision.getConstantAmount();
ArgD.Size = precision.getConstantAmount();
break;
case clang::analyze_format_string::OptionalAmount::Arg: // "%.*s"
ArgsData.back().Count = Args[precision.getArgIndex()];
if (!CheckAndSetArgExpr(precision.getArgIndex(), ArgD.Count))
return true;
break;
case clang::analyze_format_string::OptionalAmount::Invalid:
return false;
Expand All @@ -113,10 +123,11 @@ class OSLogFormatStringHandler
case clang::analyze_format_string::OptionalAmount::NotSpecified: // "%P"
return false; // length must be supplied with pointer format specifier
case clang::analyze_format_string::OptionalAmount::Constant: // "%.16P"
ArgsData.back().Size = precision.getConstantAmount();
ArgD.Size = precision.getConstantAmount();
break;
case clang::analyze_format_string::OptionalAmount::Arg: // "%.*P"
ArgsData.back().Count = Args[precision.getArgIndex()];
if (!CheckAndSetArgExpr(precision.getArgIndex(), ArgD.Count))
return true;
break;
case clang::analyze_format_string::OptionalAmount::Invalid:
return false;
Expand All @@ -125,22 +136,27 @@ class OSLogFormatStringHandler
}
default:
if (FS.getPrecision().hasDataArgument()) {
ArgsData.back().Precision = Args[FS.getPrecision().getArgIndex()];
if (!CheckAndSetArgExpr(FS.getPrecision().getArgIndex(),
ArgD.Precision))
return true;
}
break;
}
if (FS.getFieldWidth().hasDataArgument()) {
ArgsData.back().FieldWidth = Args[FS.getFieldWidth().getArgIndex()];
if (!CheckAndSetArgExpr(FS.getFieldWidth().getArgIndex(),
ArgD.FieldWidth))
return true;
}

if (FS.isSensitive())
ArgsData.back().Flags |= OSLogBufferItem::IsSensitive;
ArgD.Flags |= OSLogBufferItem::IsSensitive;
else if (FS.isPrivate())
ArgsData.back().Flags |= OSLogBufferItem::IsPrivate;
ArgD.Flags |= OSLogBufferItem::IsPrivate;
else if (FS.isPublic())
ArgsData.back().Flags |= OSLogBufferItem::IsPublic;
ArgD.Flags |= OSLogBufferItem::IsPublic;

ArgsData.back().MaskType = FS.getMaskType();
ArgD.MaskType = FS.getMaskType();
ArgsData.push_back(ArgD);
return true;
}

Expand Down
23 changes: 23 additions & 0 deletions clang/test/CodeGenObjC/os_log.m
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,13 @@ + (id)m1;

C *c;

struct S {
int a[4];
};

struct S s;
_Complex float cf;

@class NSString;
extern __attribute__((visibility("default"))) NSString *GenString(void);
void os_log_pack_send(void *);
Expand Down Expand Up @@ -123,3 +130,19 @@ void test_builtin_os_log5(void *buf) {
__builtin_os_log_format(buf, "capabilities: %@", (0, GenString()));
os_log_pack_send(buf);
}

// CHECK-LABEL: define void @test_builtin_os_log6(
// CHECK: call void @__os_log_helper_1_0_0(

void test_builtin_os_log6(void *buf) {
__builtin_os_log_format(buf, "%.*s %.*P %*.*f", s, s, s, s, s, s, s);
}

// CHECK-LABEL: define linkonce_odr hidden void @__os_log_helper_1_0_0(

// CHECK-LABEL: define void @test_builtin_os_log7(
// CHECK: call void @__os_log_helper_1_0_0(

void test_builtin_os_log7(void *buf) {
__builtin_os_log_format(buf, "%.*s %.*P %*.*f", cf, cf, cf, cf, cf, cf, cf);
}