CWE-125¶

Out-of-bounds Read. [Memory-Buffer-Errors, Improper-Control-Of-A-Resource-Through-Its-Lifetime, Top25-2024-6]

Required inputs: IR, StaticSemanticAnalysis

The product reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The product may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.

Demonstrative Examples

Example 1

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

Example Language:C
    int getValueFromArray(int *array, int len, int index) {
        int value;

        // check that the array index is less than the maximum

        // length of the array
        if (index < len) {
            // get the value at the specified index of the array
            value = array[index];
        }
        // if array index is invalid then output error message

        // and return value indicating error
        else {
            printf("Value is: %d\n", array[index]);
            value = -1;
        }

        return value;
    }

However, this method only verifies that the given array index is less than the maximum length of the array but does not check for the minimum value (CWE-839). This will allow a negative value to be accepted as the input array index, which will result in a out of bounds read (CWE-125) and may allow access to sensitive memory. The input array index should be checked to verify that is within the maximum and minimum range required for the array (CWE-129). In this example the if statement should be modified to include a minimum range check, as shown below.

Example Language:C
    ...

    // check that the array index is within the correct

    // range of values for the array
    if (index >= 0 && index < len) {

    ...

Possible Messages

Key	Text	Severity	Disabled
arithmetic_out_of_bounds	Pointer arithmetic on {node0} might create pointer outside array bounds of {name0}	None	False
out_of_bounds	Access into array is out of bounds	None	False
possible_indirect_out_of_bounds	Pointer-indirect access through {node0} might be out of bounds accessing {name0}	None	False
possible_invalid_call_argument	Call to {} with string buffer argument {} that possibly has no valid null delimiter character.	None	False
possible_out_of_bounds	Access into array might be out of bounds	None	False
undereferenced_arithmetic_out_of_bounds	Pointer arithmetic on {node0} might create pointer one past the end of {name0} (but not dereferenced)	None	False
undereferenced_out_of_bounds	Access is one past the end of the array (but not dereferenced)	None	False
undereferenced_possible_indirect_out_of_bounds	Pointer-indirect access through {node0} might be one past the end accessing {name0} (but not dereferenced)	None	False
undereferenced_possible_out_of_bounds	Access might be one past the end of the array (but not dereferenced)	None	False

Options¶

This rule shares the following common options: exclude_in_macros, exclude_messages_in_system_headers, excludes, extend_exclude_to_macro_invocations, includes, justification_checker, languages, post_processing, provider, report_at, severity
The following places define options that affect this rule: Stylechecks, Analysis-GlobalOptions

abstract_interpretation_out_of_bounds¶

abstract_interpretation_out_of_bounds : bool = False

Use additional "symbolic expression analysis" as postprocessing step. This can remove false positives, but might require more time. Option is automatically active if option StaticSemanticAnalysis/performance.general.enhanced_analysis is active.

concat_operations¶

concat_operations

Type: dict[bauhaus.analysis.config.QualifiedName, typing.Tuple[int, int]]

Default:
{
   'strcat': (0, 1)
}

Names of buffer-concatenating functions being relevant as call targets for this check, with the position of the argument pointing to the destination buffer, and the position of the argument that references the buffer that should be appended at the end of the destination buffer.

copy_operations¶

copy_operations

Type: dict[bauhaus.analysis.config.QualifiedName, typing.Tuple[int, int]]

Default:
{
   'strcpy': (0, 1)
}

Names of buffer copy functions being relevant as call targets for this check, with the position of the destination argument and the source argument of the buffer copy operation.

delimiter_of_arguments¶

delimiter_of_arguments

Type: dict[bauhaus.analysis.config.QualifiedName, set[int]]

Default:

{
   'strcat': {0, 1},
   'strchr': {0},
   'strcmp': {0, 1},
   'strcoll': {0, 1},
   'strcpy': {1},
   'strcspn': {0, 1},
   'strlen': {0},
   'strpbrk': {0, 1},
   'strrchr': {0},
   'strspn': {0, 1},
   'strstr': {0, 1},
   'strtok': {0, 1}
}

Names of functions being relevant as call targets for this check, with the position of parameters whose referenced buffers should be checked for being properly terminated by a null terminator.

exclude_very_high_indices¶

exclude_very_high_indices : bool = True

Enables heuristic to detect false positives: When index used for array access is very high in comparison to the array's size, assume false positive.

exclude_warnings_for_unknown_arguments¶

exclude_warnings_for_unknown_arguments : bool = False

Exclude warnings for cases where nothing at all is known about the arguments of an operation, caused e.g. by using return values of external routines.

ignore_calls_in_functions¶

ignore_calls_in_functions : set[bauhaus.analysis.config.QualifiedName] = set()

Qualified names of function definitions in which calls to relevant functions are ignored for this check.

report_unbounded_arrays¶

report_unbounded_arrays : bool = False

If true, accesses into arrays with unknown bound are reported as being potentially outside the allowed range. This affects arrays like extern char buf[];.

report_undereferenced_one_past_the_end¶

report_undereferenced_one_past_the_end : bool = False

If true, report accesses one past the end of an array even if there is no dereference of the resulting pointer.

report_unknown_index¶

report_unknown_index : bool = False

If false, do not report possible out-of-bound findings for which the analysis was not able to infer any restricting information about the array index (this can lead to excluding both false positives and true findings).

Axivion Suite 7.12.0

Navigation