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[analyzer] Improves the logic of GenericTaintChecker identifying stdin. 

Summary:
GenericTaintChecker can't recognize stdin in some cases. The reason is that `if (PtrTy->getPointeeType() == C.getASTContext().getFILEType()` does not hold when stdin is encountered.

My platform is ubuntu16.04 64bit, gcc 5.4.0, glibc 2.23. The definition of stdin is as follows:
```
__BEGIN_NAMESPACE_STD
/* The opaque type of streams.  This is the definition used elsewhere.  */
typedef struct _IO_FILE FILE;
___END_NAMESPACE_STD

  ...

/* The opaque type of streams.  This is the definition used elsewhere.  */
typedef struct _IO_FILE __FILE;   

  ...

/* Standard streams.  */
extern struct _IO_FILE *stdin;      /* Standard input stream.  */
extern struct _IO_FILE *stdout;     /* Standard output stream.  */
extern struct _IO_FILE *stderr;     /* Standard error output stream.  */
```

The type of stdin is as follows AST:
```
ElaboratedType 0xc911170'struct _IO_FILE'sugar
`-RecordType 0xc911150'struct _IO_FILE'
 `-CXXRecord 0xc923ff0'_IO_FILE'
```

`C.getASTContext().GetFILEType()` is as follows AST:
```
TypedefType 0xc932710 'FILE' sugar
|-Typedef 0xc9111c0 'FILE'
`-ElaboratedType 0xc911170 'struct _IO_FILE' sugar
  `-RecordType 0xc911150 'struct _IO_FILE'
      `-CXXRecord 0xc923ff0 '_IO_FILE'
```

So I think it's better to use `getCanonicalType()`.

Reviewers: zaks.anna, NoQ, george.karpenkov, a.sidorin

Reviewed By: zaks.anna, a.sidorin

Subscribers: a.sidorin, cfe-commits, xazax.hun, szepet, MTC

Differential Revision: https://reviews.llvm.org/D39159

llvm-svn: 326709
This commit is contained in:
Henry Wong 2018-03-05 15:41:15 +00:00
parent 7d697857cd
commit cb2ad24c5c
2 changed files with 8 additions and 1 deletions
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3
clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp
View File

@ -646,7 +646,8 @@ bool GenericTaintChecker::isStdin(const Expr *E, CheckerContext &C) {
if ((D->getName().find("stdin") != StringRef::npos) && D->isExternC())
if (const PointerType * PtrTy =
dyn_cast<PointerType>(D->getType().getTypePtr()))
if (PtrTy->getPointeeType() == C.getASTContext().getFILEType())
if (PtrTy->getPointeeType().getCanonicalType() ==
C.getASTContext().getFILEType().getCanonicalType())
return true;
}
return false;

6
clang/test/Analysis/taint-generic.c
View File

@ -1,10 +1,16 @@
// RUN: %clang_analyze_cc1 -analyzer-checker=alpha.security.taint,core,alpha.security.ArrayBoundV2 -Wno-format-security -verify %s
// RUN: %clang_analyze_cc1 -DFILE_IS_STRUCT -analyzer-checker=alpha.security.taint,core,alpha.security.ArrayBoundV2 -Wno-format-security -verify %s
int scanf(const char *restrict format, ...);
int getchar(void);
typedef struct _FILE FILE;
#ifdef FILE_IS_STRUCT
extern struct _FILE *stdin;
#else
extern FILE *stdin;
#endif
int fscanf(FILE *restrict stream, const char *restrict format, ...);
int sprintf(char *str, const char *format, ...);
void setproctitle(const char *fmt, ...);