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C

C static code analysis

Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code

  • All rules 315
  • Vulnerability13
  • Bug76
  • Security Hotspot19
  • Code Smell207

  • Quick Fix 19
Filtered: 35 rules found
symbolic-execution
    Impact
      Clean code attribute
        1. The address of an automatic object should not be assigned to another object that may persist after the first object has ceased to exist

           Bug
        2. Variables should be initialized before use

           Bug
        3. Variables should not be accessed outside of their scope

           Bug
        4. Account validity should be verified when authenticating users with PAM

           Vulnerability
        5. Changing directories improperly when using "chroot" is security-sensitive

           Security Hotspot
        6. POSIX functions should not be called with arguments that trigger buffer overflows

           Vulnerability
        7. Server hostnames should be verified during SSL/TLS connections

           Vulnerability
        8. "pthread_mutex_t" should be unlocked in the reverse order they were locked

           Bug
        9. Only valid arguments should be passed to UNIX/POSIX functions

           Code Smell
        10. "pthread_mutex_t" should be properly initialized and destroyed

           Bug
        11. "pthread_mutex_t" should not be locked when already locked, or unlocked when already unlocked

           Bug
        12. Only valid arguments should be passed to stream functions

           Code Smell
        13. Using publicly writable directories is security-sensitive

           Security Hotspot
        14. Using clear-text protocols is security-sensitive

           Security Hotspot
        15. Blocking functions should not be called inside critical sections

           Code Smell
        16. Return value of "setuid" family of functions should always be checked

           Code Smell
        17. Size of variable length arrays should be greater than zero

           Code Smell
        18. "mktemp" family of functions templates should have at least six trailing "X"s

           Code Smell
        19. Appropriate size arguments should be passed to "strncat" and "strlcpy"

           Code Smell
        20. Server certificates should be verified during SSL/TLS connections

           Vulnerability
        21. Weak SSL/TLS protocols should not be used

           Vulnerability
        22. Integral operations should not overflow

           Bug
        23. Parameter values should be appropriate

           Bug
        24. Stack allocated memory and non-owned memory should not be freed

           Bug
        25. Closed resources should not be accessed

           Bug
        26. Dynamically allocated memory should be released

           Bug
        27. Freed memory should not be used

           Bug
        28. Memory locations should not be released more than once

           Bug
        29. Memory access should be explicitly bounded to prevent buffer overflows

           Bug
        30. Zero should not be a possible denominator

           Bug
        31. XML parsers should not be vulnerable to XXE attacks

           Vulnerability
        32. "nonnull" parameters and return values of "returns_nonnull" functions should not be null

           Bug
        33. Null pointers should not be dereferenced

           Bug
        34. Resources should be closed

           Bug
        35. Unused assignments should be removed

           Code Smell

        Parameter values should be appropriate

        intentionality - logical
        reliability
        Bug
        • symbolic-execution

        Passing NULL to a C library function that requires non-null pointer arguments results in undefined behavior.

        Why is this an issue?

        What is the potential impact?

        How can I fix it?

        More Info

        The standard C library includes a variety of functions for string and general memory manipulations. Many of these functions require valid parameters and when given values outside a function’s domain, the behavior is undefined. Functions like strlen, memset, memcpy, qsort, fread, etc., for instance, require non-NULL parameters, and passing a NULL value introduces undefined behavior. In that case, the application may crash or, even worse, silently lose data or produce incorrect results.

        Consider the following code. If the pointer-typed variable buf is NULL due to a failed memory allocation, for instance, the call to memset() will cause undefined behavior.

        #include <string.h>
        
        void process_buffer(char *buf, size_t size) {
          // Call to `memset()` may lead to undefined behavior, if `buf` is NULL.
          memset(buf, 0, size);
        }
        

        Similarly, if for some reason a NULL pointer slips through and reaches the string manipulation code shown in the following, the application’s behavior is undefined.

        #include <string.h>
        
        int compare_strings(const char *str_a, const char *str_b) {
          // Both functions `strlen()` and `strncmp()` may not receive a `NULL` pointer.
          size_t len_a = strlen(str_a);
          size_t len_b = strlen(str_b);
          size_t min = (len_a <= len_b) ? len_a : len_b;
          return strncmp(str_a, str_b, min);
        }
        

        Hence, users have to ensure that the C standard library functions' preconditions are met and valid parameters are passed.

        The C library functions that are considered by this rule and that require non-NULL pointer parameters are listed in this rule’s Resources section.

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