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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: 59 rules found
cwe
    Impact
      Clean code attribute
        1. Function-like macros should not be invoked without all of their arguments

           Bug
        2. Function exit paths should have appropriate return values

           Bug
        3. The number of arguments passed to a function should match the number of parameters

           Bug
        4. Non-empty statements should change control flow or have at least one side-effect

           Bug
        5. Bitwise operators should not be applied to signed operands

           Bug
        6. Limited dependence should be placed on operator precedence

           Code Smell
        7. Variables should be initialized before use

           Bug
        8. Hard-coded secrets are security-sensitive

           Security Hotspot
        9. "sprintf" should not be used

           Security Hotspot
        10. Changing working directories without verifying the success is security-sensitive

           Security Hotspot
        11. Setting capabilities is security-sensitive

           Security Hotspot
        12. Accessing files should not introduce TOCTOU vulnerabilities

           Vulnerability
        13. Account validity should be verified when authenticating users with PAM

           Vulnerability
        14. Using "tmpnam", "tmpnam_s" or "tmpnam_r" is security-sensitive

           Security Hotspot
        15. Using "strncpy" or "wcsncpy" is security-sensitive

           Security Hotspot
        16. Using "strncat" or "wcsncat" is security-sensitive

           Security Hotspot
        17. Using "strcat" or "wcscat" is security-sensitive

           Security Hotspot
        18. Using "strlen" or "wcslen" is security-sensitive

           Security Hotspot
        19. Changing directories improperly when using "chroot" is security-sensitive

           Security Hotspot
        20. Using "strcpy" or "wcscpy" is security-sensitive

           Security Hotspot
        21. "memset" should not be used to delete sensitive data

           Vulnerability
        22. POSIX functions should not be called with arguments that trigger buffer overflows

           Vulnerability
        23. Cipher algorithms should be robust

           Vulnerability
        24. Encryption algorithms should be used with secure mode and padding scheme

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

           Vulnerability
        26. "pthread_mutex_t" should not be locked when already locked, or unlocked when already unlocked

           Bug
        27. Using publicly writable directories is security-sensitive

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

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

           Code Smell
        30. Expanding archive files without controlling resource consumption is security-sensitive

           Security Hotspot
        31. Server certificates should be verified during SSL/TLS connections

           Vulnerability
        32. Using weak hashing algorithms is security-sensitive

           Security Hotspot
        33. Cryptographic keys should be robust

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

           Vulnerability
        35. Dynamically allocated memory should be released

           Bug
        36. Freed memory should not be used

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

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

           Bug
        39. Zero should not be a possible denominator

           Bug
        40. "sizeof" should not be called on pointers

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

           Vulnerability
        42. Multiline blocks should be enclosed in curly braces

           Code Smell
        43. "nonnull" parameters and return values of "returns_nonnull" functions should not be null

           Bug
        44. Setting loose POSIX file permissions is security-sensitive

           Security Hotspot
        45. Conditionally executed code should be reachable

           Bug
        46. Null pointers should not be dereferenced

           Bug
        47. Using pseudorandom number generators (PRNGs) is security-sensitive

           Security Hotspot
        48. Resources should be closed

           Bug
        49. Hard-coded passwords are security-sensitive

           Security Hotspot
        50. Code annotated as deprecated should not be used

           Code Smell
        51. Unused assignments should be removed

           Code Smell
        52. All code should be reachable

           Bug
        53. "switch" statements should have "default" clauses

           Code Smell
        54. Switch cases should end with an unconditional "break" statement

           Code Smell
        55. Track uses of "TODO" tags

           Code Smell
        56. Track uses of "FIXME" tags

           Code Smell
        57. Assignments should not be made from within conditions

           Code Smell
        58. Insecure functions should not be used

           Vulnerability
        59. "scanf()" and "fscanf()" format strings should specify a field width for the "%s" string placeholder

           Vulnerability

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

        intentionality - logical
        reliability
        Bug
        • cwe
        • symbolic-execution
        • cert

        Pointers marked as "nonnull" may not be set to null, since they are typically not null-checked before use.

        Why is this an issue?

        What is the potential impact?

        How can I fix it?

        More Info

        A function’s return value and parameters may be decorated with attributes to convey additional information to the compiler and/or other developers.

        A commonly used attribute is nonnull which can be used to mark a function’s return value and parameters as shown in the following:

        #include <stdlib.h>
        #include <stdio.h>
        #include <string.h>
        
        __attribute__((returns_nonnull)) int *
        make_array_copy(int *src, size_t len) __attribute__((nonnull(1)));
        
        int *make_array_copy(int *src, size_t len) {
          int *dst = (int *)malloc(len * sizeof(int));
          if (dst == NULL) {
            perror("malloc failed");
            exit(1);
          }
          memcpy(dst, src, len);
          return dst;
        }
        

        The nonnull attribute is meant for other developers and as a hint for compilers. Values marked as nonnull are assumed to have non-null values.

        However, developers may accidentally break the nonnull attribute as shown in the following code snippet:

        __attribute__((returns_nonnull))
        int *foo(__attribute__((nonnull)) int *x) {
          x = 0; // This is compliant but might be surprising, use with caution
          foo(0); // Noncompliant: null is passed as an argument marked as "nonnull"
          return 0; // Noncompliant: return value is marked "nonnull" but null is returned
        }
        

        Failing to adhere to the attribute may introduce serious program errors. In particular, the compiler does not enforce that values marked as nonnull are indeed non-null at runtime; it is the developers' responsibility to adhere to the attribute. These values are typically not null-checked before use. Passing null (i.e., NULL, 0 or nullptr) as an argument to a parameter that is marked as nonnull or returning null from a function marked as returns_nonnull is, hence, likely to cause a null-pointer dereference. Compilers may even apply optimizations based on this attribute and might, for instance, remove an explicit null-check if the parameter is declared as nonnull — even in code outside of the function with the attribute.

        Note that the nonnull attribute is a GNU extension (see nonnull and returns_nonnull) which many compiler vendors have implemented.

        Note that it is allowed to assign null to a parameter marked as nonnull. This attribute is only concerned with the function call contract and does not control the evolution of the parameter variable. For example, a linked-list search could be implemented as follows:

        struct List {
          int value;
          List *next; // nullptr for a tail node.
        };
        
        
        List *findElement(List *l, int elem) __attribute__((nonnull(1)));
        
        List *findElement(List *l, int elem) {
          while(l && l->value != elem)
            l = l->next;
          return l;
        }
        
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