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Non-Compliant Code Example
Wiki Markup main(), called at program startup, is typically declared as follows when the program accepts command line arguments:
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int main(int argc, char *argv[]) { /* ... */ }
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from the command line and stored in process memory. Command line arguments are passed to {{main()}} as pointers to null-terminated byte strings in the array members {{argv\[0\]}} through {{argv\[argc-1\]}}. |
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If the value of {{argc}} is greater than zero, the string pointed to by {{argv\[0\]}} represents the program name. If the value of {{argc}} is greater than one, the strings pointed to by {{argv\[1\]}} through {{argv\[argc-1\]}} represent the program parameters.
In the following definition for {{main()}} the array members {{argv\[0\]}} through {{argv\[argc-1\]}} inclusive contain pointers to null-terminated byte strings. |
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int main(int argc, char *argv[]) { /* ... */ }
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IfThe theparameters value of {{argc}} is greater than zero,and {{argv}} and the stringstrings pointed to by the {{argv\[0\]}} representsarray are not modifiable by the program name. If the value of argc is greater than one, the strings pointed to by {{argv\[1\]}} through {{argv\[argc-1\]}} represent the program parameters. |
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The, and retain their last-stored values between program startup and program termination. This requires that a copy of these parameters be made before the strings can be modified. Vulnerabilities can occur when inadequate space is allocated to copy a command line argument. In this example, the contents of {{argv\[0\]}} can be manipulated by an attacker to cause a buffer overflow in the following program: |
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int main(int argc, char *argv[]) {
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char prog_name[128];
strcpy(prog_name, argv[0]);
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}
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