SEI CERT C Coding Standard

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changes.mady.by.user Will Snavely

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New Version 92

changes.mady.by.user Arthur Hicken

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Incorrectly assuming that character data has been read can result in an out-of-bounds memory write or other flawed logic.

Rule

Severity

Likelihood

Remediation Cost

Priority

Level

FIO37-C

High

Probable

Medium

P12

L1

Automated Detection

Tool

Version

Checker

Description

Astrée
Include Page
Astrée_V
Astrée_V
 

Supported, but no explicit checker
CodeSonar
Include Page
CodeSonar_V
CodeSonar_V
(general)Considers the possibility that fgets() and fgetws() may return empty strings (Warnings of various classes may be triggered depending on subsequent operations on those strings. For example, the noncompliant code example cited above would trigger a buffer underrun warning.)
Compass/ROSE

 

 



Could detect some violations of this rule (In particular, it could detect the noncompliant code example by searching for fgets(), followed by strlen() - 1, which could be −1. The crux of this rule is that a string returned by fgets() could still be empty, because the first char is '\0'. There are probably other code examples that violate this guideline; they would need to be enumerated before ROSE could detect them.)

LDRA tool suite
Include Page
LDRA_V
LDRA_V
44 SEnhanced enforcement
Parasoft C/C++test
Include Page
c:
Parasoft_V
c:
Parasoft_V
BD-PB-ARRAYFully implemented
PRQA QA-C++4.2 2840, 2841, 2842, 2843, 2844
 

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

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Key here (explains table format and definitions)

Taxonomy

Taxonomy item

Relationship

CERT C Secure Coding StandardFIO14-C. Understand the difference between text mode and binary mode with file streamsPrior to 2018-01-12: CERT: Unspecified Relationship
CERT C Secure Coding StandardFIO20-C. Avoid unintentional truncation when using fgets() or fgetws()Prior to 2018-01-12: CERT: Unspecified Relationship
CWE 2.11CWE-241, Improper Handling of Unexpected Data Type2017-07-05: CERT: Rule subset of CWE

CERT-CWE Mapping Notes

Key here for mapping notes

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  • Improper handling of unexpected data type that does not come from the fgets() function.


Bibliography

[ISO/IEC 9899:2011]

Subclause 7.21.7.2, "The fgets Function"
Subclause 7.29.3.2, "The fgetws Function"

[Lai 2006]
 

[Seacord 2013]Chapter 2, "Strings"

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