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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

        "pthread_mutex_t" should not be locked when already locked, or unlocked when already unlocked

        intentionality - logical
        reliability
        Bug
        • cwe
        • symbolic-execution
        • multi-threading

        pthread_mutex_t should not be locked when already locked, or unlocked when already unlocked.

        Why is this an issue?

        How can I fix it?

        More Info

        Mutexes are synchronization primitives that allow to manage concurrency. This is the most fundamental building block for creating safe concurrent applications. By using a mutex, one can ensure that a block of code is executed by a single thread concurrently. Data structures are designed to maintain their invariants between member-function calls. If a data structure is accessed concurrently, and one of the accesses is a write operation, then it has a data race. Having data races is undefined behavior.

        Adversaries actively exploit data races to take over systems, but data races are also a common source of data corruption in concurrent applications resulting in dormant and hard-to-find bugs.

        To prevent data races, the shared resource (usually memory) must be protected by obtaining mutual access to the data during both reading and writing. Such mutual exclusion is generally achieved by using a mutex, which is frequently referred to as a lock.

        A mutex has two states: released - which is the initial state, or acquired. These two states are frequently called unlocked and locked as well.

        To effectively protect the shared resource from concurrent accesses, all such accesses should be guarded by the same mutex. They need to lock the mutex to gain safe exclusive access to the resource and unlock it after they are done mutating or reading it.

        You can abstract away the concurrent threads sharing the mutex and think of it as owned by the current thread. It never spontaneously changes between acquired and released.

        In this view, these are the possible transitions when calling lock or unlock on a mutex in a given state:

        1. released + lock() ⇒ acquired
        2. acquired + unlock() ⇒ released
        3. acquired + lock() ⇒ deadlock
        4. released + unlock() ⇒ undefined behavior

        When a thread locks a mutex, another thread trying to acquire the same mutex will be blocked and have to wait for the first thread to release it. This waiting period can take some time. If a thread attempts to lock a mutex it has already acquired, it will deadlock because it would need to release it to lock it again.

        What is the potential impact?

        Locking an acquired mutex leads to a deadlock, as a mutex can only be obtained once. Unlocking a released mutex is undefined behavior. Removing synchronization can cause data races, leading to data corruption, which adversaries might leverage to take over the system.

        Exceptions

        There are recursive mutexes that can be acquired multiple times by the same thread, given that just as many times we also release the mutex. They are rare in practice and usually signal design problems in the code. Thus we assume pthread_mutex_t refers to non-recursive mutexes.

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