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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

        Dynamically allocated memory should be released

        intentionality - complete
        reliability
        Bug
        • cwe
        • symbolic-execution
        • leak
        • denial-of-service
        • cert

        Memory allocated dynamically with calloc, malloc, realloc, or new should be released when it is not needed anymore. Failure to do so will result in a memory leak that could severely hinder application performance or abort it or the entire host machine.

        Why is this an issue?

        How can I fix it?

        More Info

        Memory is a limited resource shared between all the applications running on the same host machine.

        C and C++ do not automatically reclaim unused memory. The developer has to release the memory claimed for their application that is no longer needed. Unlike the stack that automatically allocates local variables on a function call and deallocates them on a function return, the heap offers no automatic memory management. The developer has to make sure to deallocate the memory they allocate dynamically on the heap.

        This rule raises an issue when memory is allocated dynamically and not freed within the same function.

        What is the potential impact?

        Neglecting to free the memory leads to a memory leak.

        The application that leaks memory will consume more and more of it over time, eventually claiming all the memory available on the host machine. When this happens and the system runs out of memory, it typically does one of the following:

        • The operating system (if any) terminates the application.
        • The operating system (if any) terminates some other application, and the problem reoccurs when the reclaimed memory gets used up by the leaking application.
        • The operating system (if any) starts offloading some of the memory pages to disk and slows down some memory accesses by orders of magnitude.
        • The entire system crashes as a whole and reboots automatically or hangs waiting for a manual reboot.

        Moreover, memory leaks can help an attacker to take over the system. An attacker could use a memory leak to fill the memory with malicious code. This facilitates remote code execution through another chained vulnerability.

        Even if the attacker cannot take over the system she can intentionally trigger the condition leading to a memory leak to make use of the issue above and cause denial-of-service (DoS) of the system.

        A memory leak can have a significant impact on the energy footprint of an application.

        • If an application demands more memory than necessary, the user will have to install more memory banks than necessary. Each memory bank consumes additional power.
        • As the application continues to reserve more and more memory, it places an increased load on the memory management subsystem. This increased load can lead to a larger computation demand, which in turn translates to higher power consumption by the CPU.

        Finally, memory leaks degrade the user experience. The user often experiences a system slowdown caused by the uncontrolled memory use of an application. Delayed response time, system freezes, and crashes degrade the user experience and discourage the further use of the application.

        Exceptions

        If a function returns a pointer to the caller or stores it in an external structure, this pointer is said to escape (it is now accessible outside of function, and no longer local to it). This includes storing the pointer in a static or global variable, passing it to a function that can potentially do that, or returning the pointer directly or as part of an aggregate object.

        The memory pointed to by an escaping pointer might be used somewhere else in the program. For that reason, the analyzer cannot proclaim a leak for an escaping pointer by only looking at a function scope.

        While in some cases the leak might be detectable in the scope of a caller, in others, the analyzer would need to simulate the entire program to verify that the memory is not used anywhere, which is not feasible.

        For this technical reason, this rule often ignores escaping pointers.

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