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The following code illustrates how the managed string library can be used to create a managed string and retrieve a null-terminated byte string from the managed string.
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errno_t retValue;
char *cstr; /* pointer to null-terminated byte string */
string_m str1 = NULL;
retValue = strcreate_m(&str1, "hello, world", 0, NULL);
if (retValue != 0)) {
fprintf(stderr, "Error %d from strcreate_m.\n", retValue);
}
else { /* retrieve null-terminated byte string and print */
retValue = getstr_m(&cstr, str1);
if (retValue != 0) {
fprintf(stderr, "error %d from getstr_m.\n", retValue);
}
printf("(%s)\n", cstr);
free(cstr); /* free null-terminated byte string */
cstr = NULL;
}
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Note that the calls to {{fprintf()}} and {{printf()}} are C99 \[[ISO/IEC 9899-1999|AA. C References#ISO/IEC 9899-1999]\] standard functions and not managed string functions. |
The forthcoming technical report ISO/IEC TR 24731 Part II will also provide an API that dynamically allocates the results of string functions as needed.
Risk Assessment
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String handling functions defined in C99 \[[ISO/IEC 9899-1999|AA. C References#ISO/IEC 9899-1999]\] Section 7.21 and elsewhere are susceptible to common programming errors that can lead to serious, exploitable [vulnerabilities|BB. Definitions#vulnerability]. Managed strings, when used properly, can eliminate many of these errors, particularly in new development. |
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level | |||
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STR01-A | 3 (high) | 2 (probable) | 1 (high) | low | low | high | P3 P6 | L2 |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
References
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\[[Burch 06|AA. C References#Burch06]\] \[[CERT 06c|AA. C References#CERT 06c]\] \[[ISO/IEC 9899-1999|AA. C References#ISO/IEC 9899-1999]\] Section 7.21, "String handling <string.h>" \[[Seacord 05a|AA. C References#Seacord 05a]\] Chapter 2, "Strings" |
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