From: Ted Kremenek <kremenek@apple.com>
Date: Tue, 20 Jul 2010 20:04:47 +0000 (+0000)
Subject: Hookup checking for invalid length modifiers in scanf format strings.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1e51c200b17cb6b0238c10a8760ae04765688f16;p=clang

Hookup checking for invalid length modifiers in scanf format strings.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108907 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ScanfFormatString.cpp b/lib/Analysis/ScanfFormatString.cpp
index 493a3c8df2..61af1d6737 100644
--- a/lib/Analysis/ScanfFormatString.cpp
+++ b/lib/Analysis/ScanfFormatString.cpp
@@ -19,6 +19,7 @@ using clang::analyze_format_string::ArgTypeResult;
 using clang::analyze_format_string::FormatStringHandler;
 using clang::analyze_format_string::LengthModifier;
 using clang::analyze_format_string::OptionalAmount;
+using clang::analyze_format_string::ConversionSpecifier;
 using clang::analyze_scanf::ScanfConversionSpecifier;
 using clang::analyze_scanf::ScanfSpecifier;
 
@@ -146,27 +147,28 @@ static ScanfSpecifierResult ParseScanfSpecifier(FormatStringHandler &H,
   switch (*conversionPosition) {
     default:
       break;
-    case '%': k = ScanfConversionSpecifier::PercentArg;   break;
-    case 'A': k = ScanfConversionSpecifier::AArg; break;
-    case 'E': k = ScanfConversionSpecifier::EArg; break;
-    case 'F': k = ScanfConversionSpecifier::FArg; break;
-    case 'G': k = ScanfConversionSpecifier::GArg; break;
-    case 'X': k = ScanfConversionSpecifier::XArg; break;
-    case 'a': k = ScanfConversionSpecifier::aArg; break;
-    case 'd': k = ScanfConversionSpecifier::dArg; break;
-    case 'e': k = ScanfConversionSpecifier::eArg; break;
-    case 'f': k = ScanfConversionSpecifier::fArg; break;
-    case 'g': k = ScanfConversionSpecifier::gArg; break;
-    case 'i': k = ScanfConversionSpecifier::iArg; break;
-    case 'n': k = ScanfConversionSpecifier::nArg; break;
-    case 'c': k = ScanfConversionSpecifier::cArg; break;
-    case 'C': k = ScanfConversionSpecifier::CArg; break;
-    case 'S': k = ScanfConversionSpecifier::SArg; break;
-    case '[': k = ScanfConversionSpecifier::ScanListArg; break;
-    case 'u': k = ScanfConversionSpecifier::uArg; break;
-    case 'x': k = ScanfConversionSpecifier::xArg; break;
-    case 'o': k = ScanfConversionSpecifier::oArg; break;
-    case 's': k = ScanfConversionSpecifier::sArg; break;
+    case '%': k = ConversionSpecifier::PercentArg;   break;
+    case 'A': k = ConversionSpecifier::AArg; break;
+    case 'E': k = ConversionSpecifier::EArg; break;
+    case 'F': k = ConversionSpecifier::FArg; break;
+    case 'G': k = ConversionSpecifier::GArg; break;
+    case 'X': k = ConversionSpecifier::XArg; break;
+    case 'a': k = ConversionSpecifier::aArg; break;
+    case 'd': k = ConversionSpecifier::dArg; break;
+    case 'e': k = ConversionSpecifier::eArg; break;
+    case 'f': k = ConversionSpecifier::fArg; break;
+    case 'g': k = ConversionSpecifier::gArg; break;
+    case 'i': k = ConversionSpecifier::iArg; break;
+    case 'n': k = ConversionSpecifier::nArg; break;
+    case 'c': k = ConversionSpecifier::cArg; break;
+    case 'C': k = ConversionSpecifier::CArg; break;
+    case 'S': k = ConversionSpecifier::SArg; break;
+    case '[': k = ConversionSpecifier::ScanListArg; break;
+    case 'u': k = ConversionSpecifier::uArg; break;
+    case 'x': k = ConversionSpecifier::xArg; break;
+    case 'o': k = ConversionSpecifier::oArg; break;
+    case 's': k = ConversionSpecifier::sArg; break;
+    case 'p': k = ConversionSpecifier::pArg; break;
   }
   ScanfConversionSpecifier CS(conversionPosition, k);
   if (k == ScanfConversionSpecifier::ScanListArg) {
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 8846c25724..2887a50d52 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1701,9 +1701,17 @@ bool CheckScanfHandler::HandleScanfSpecifier(
     CoveredArgs.set(argIndex);
   }
   
-  // FIXME: Check that the length modifier is valid with the given
-  // conversion specifier.
-  
+  // Check the length modifier is valid with the given conversion specifier.
+  const LengthModifier &LM = FS.getLengthModifier();
+  if (!FS.hasValidLengthModifier()) {
+    S.Diag(getLocationOfByte(LM.getStart()),
+           diag::warn_format_nonsensical_length)
+      << LM.toString() << CS.toString()
+      << getSpecifierRange(startSpecifier, specifierLen)
+      << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(),
+                                                    LM.getLength()));
+  }
+
   // The remaining checks depend on the data arguments.
   if (HasVAListArg)
     return true;
diff --git a/test/Sema/format-strings-scanf.c b/test/Sema/format-strings-scanf.c
index 68552b3e24..42b6c03ffb 100644
--- a/test/Sema/format-strings-scanf.c
+++ b/test/Sema/format-strings-scanf.c
@@ -2,6 +2,7 @@
 
 typedef __typeof(sizeof(int)) size_t;
 typedef struct _FILE FILE;
+typedef __WCHAR_TYPE__ wchar_t;
 
 int fscanf(FILE * restrict, const char * restrict, ...) ;
 int scanf(const char * restrict, ...) ;
@@ -24,3 +25,10 @@ void test(const char *s, int *i) {
   scanf("%*d", i); // // expected-warning{{data argument not used by format string}}
   scanf("%*d%1$d", i); // no-warning
 }
+
+void bad_length_modifiers(char *s, void *p, wchar_t *ws, long double *ld) {
+  scanf("%hhs", "foo"); // expected-warning{{length modifier 'hh' results in undefined behavior or no effect with 's' conversion specifier}}
+  scanf("%1$zp", p); // expected-warning{{length modifier 'z' results in undefined behavior or no effect with 'p' conversion specifier}}
+  scanf("%ls", ws); // no-warning
+  scanf("%#.2Lf", ld); // expected-warning{{invalid conversion specifier '#'}}
+}