Page History

...

Code Block

bgColor	#ccccff
lang	c

#include <png.h> /* From libpng */
#include <string.h>

 void func(png_structp png_ptr, size_t length, const void *user_data) { 
  png_charp chunkdata;
  if (length == SIZE_MAX) {
    /* Handle error */
  }
  if (NULL == user_data) {
    /* Handle error */
  }
  chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
  if (NULL == chunkdata) {
    /* Handle error */
  }
  if (NULL ==/* ... */
  memcpy(chunkdata, user_data) {
    /* Handle error */
  }
  /* ... */
  memcpy(chunkdata, user_data, length), length);
  /* ... */

 }

Noncompliant Code Example

...

CERT C: Rule EXP34-C

2810, 2811, 2812, 2813

Tool Version Checker Description

Astrée

Include Page

	Astrée_V
	Astrée_V

null-dereferencing

Fully checked

Axivion Bauhaus Suite

Include Page

	Axivion Bauhaus Suite_V
	Axivion Bauhaus Suite_V

CertC-EXP34

CodeSonar

Include Page

	CodeSonar_V
	CodeSonar_V

LANG.MEM.NPD
LANG.STRUCT.NTAD
LANG.STRUCT.UPD

Null pointer dereference
Null test after dereference
Unchecked parameter dereference

Compass/ROSE

Can detect violations of this rule. In particular, ROSE ensures that any pointer returned by malloc(), calloc(), or realloc() is first checked for NULL before being used (otherwise, it is free()-ed). ROSE does not handle cases where an allocation is assigned to an lvalue that is not a variable (such as a struct member or C++ function call returning a reference)

Coverity

Include Page

	Coverity_V
	Coverity_V

CHECKED_RETURN

NULL_RETURNS

REVERSE_INULL

FORWARD_NULL

Finds instances where a pointer is checked against NULL and then later dereferenced

Identifies functions that can return a null pointer but are not checked

Identifies code that dereferences a pointer and then checks the pointer against NULL

Can find the instances where NULL is explicitly dereferenced or a pointer is checked against NULL but then dereferenced anyway. Coverity Prevent cannot discover all violations of this rule, so further verification is necessary

Cppcheck

Include Page

	Cppcheck_V
	Cppcheck_V

nullPointer, nullPointerDefaultArg, nullPointerRedundantCheck

Context sensitive analysis

Detects when NULL is dereferenced (Array of pointers is not checked. Pointer members in structs are not checked.)

Finds instances where a pointer is checked against NULL and then later dereferenced

Identifies code that dereferences a pointer and then checks the pointer against NULL

Does not guess that return values from malloc(), strchr(), etc., can be NULL (The return value from malloc() is NULL only if there is OOMo and the dev might not care to handle that. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL.)

Helix QAC

Include Page

	Helix QAC_V
	Helix QAC_V

DF2810, DF2811, DF2812, DF2813

Fully implemented

C: 2810, 2811, 2812, 2813

C++: 2810, 2811, 2812, 2813

Klocwork

Include Page

	Klocwork_V
	Klocwork_V

NPD.CHECK.CALL.MIGHT
NPD.CHECK.CALL.MUST
NPD.CHECK.MIGHT
NPD.CHECK.MUST
NPD.CONST.CALL
NPD.CONST.DEREF
NPD.FUNC.CALL.MIGHT
NPD.FUNC.CALL.MUST
NPD.FUNC.MIGHT
NPD.FUNC.MUST
NPD.GEN.CALL.MIGHT
NPD.GEN.CALL.MUST
NPD.GEN.MIGHT
NPD.GEN.MUST
RNPD.CALL
RNPD.DEREF