SEI CERT C Coding Standard

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Comment: REM Cost Reform

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This compliant solution declares c wc to be a wint_t to match the integer type returned by getwc(). Furthermore, it does not rely on WEOF to determine end-of-file definitively.

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Incorrectly assuming characters from a file cannot match EOF or WEOF has resulted in significant vulnerabilities, including command injection attacks. (See the *CA-1996-22 advisory.)

Rule

Severity

Likelihood

Detectable

Remediation Cost

Repairable

Priority

Level

FIO34-C

High

Probable

Yes

MediumYes

P12P18

L1


Automated Detection

Avoid implicit conversions from wider to narrower types

Tool

Version

Checker

Description

Astrée
Include Page
Astrée_V
Astrée_V

conversion_overflow

essential-type-assign

Soundly supported
Axivion Bauhaus Suite

Include Page
Axivion Bauhaus Suite_V
Axivion Bauhaus Suite_V

CertC-FIO34
CodeSonar
Include Page
CodeSonar_V
CodeSonar_V
LANG.CAST.COERCECoercion alters value
Compass/ROSE




Coverity
Include Page
Coverity_V
Coverity_V

CHAR_IO

Identifies defects when the return value of fgetc(), getc(), or getchar() is incorrectly assigned to a char instead of an int. Coverity Prevent cannot discover all violations of this rule, so further verification is necessary

Cppcheck Premium
Include Page
Cppcheck Premium_V
Cppcheck Premium_V


premium-cert-fio34-c


ECLAIR1.2

CC2.FIO34

Partially implemented

Helix QAC

Include Page
Helix QAC_V
Helix QAC_V

C2676, C2678

C++2676, C++2678, C++3001, C++3010, C++3051, C++3137, C++3717


Klocwork
Include Page
Klocwork_V
Klocwork_V
CWARN.CMPCHR.EOF
LDRA tool suite
Include Page
LDRA_V
LDRA_V
662 S
Fully implemented
Parasoft C/C++test
Include Page
Parasoft_V
Parasoft_V

CERT_C-FIO34-a

The macro EOF should be compared with the unmodified return value from the Standard Library function

Polyspace Bug Finder

Include Page
Polyspace Bug Finder_V
Polyspace Bug Finder_V

CERT C: Rule FIO34-C


Checks for character values absorbed into EOF (rule partially covered)

PRQA QA-C
Include Page
PRQA QA-C_vPRQA QA-C_v2676, 2678PRQA QA-C++
Include Page
cplusplus:PRQA QA-C++_Vcplusplus:PRQA QA-C++_V
Splint3.1.1



RuleChecker

Include Page
RuleChecker_V
RuleChecker_V

essential-type-assignSupported2676, 2678, 3001, 3010, 3051, 3137, 3717Splint3.1.1

Related Vulnerabilities

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

Related Guidelines

Key here (explains table format and definitions)

Taxonomy

Taxonomy item

Relationship

CERT C Secure Coding StandardSTR00-C. Represent characters using an appropriate typePrior to 2018-01-12: CERT: Unspecified Relationship
CERT C Secure Coding StandardINT31-C. Ensure that integer conversions do not result in lost or misinterpreted dataPrior to 2018-01-12: CERT: Unspecified Relationship
CERT Oracle Secure Coding Standard for JavaFIO08-J. Use an int to capture the return value of methods that read a character or bytePrior to 2018-01-12: CERT: Unspecified Relationship
ISO/IEC TS 17961:2013Using character values that are indistinguishable from EOF [chreof]Prior to 2018-01-12: CERT: Unspecified Relationship
CWE 2.11CWE-1972017-06-14: CERT: Rule subset of CWE

CERT-CWE Mapping Notes

Key here for mapping notes

CWE-197 and FIO34-C

Independent( FLP34-C, INT31-C) FIO34-C = Subset( INT31-C)

Therefore: FIO34-C = Subset( CWE-197)

Bibliography

[Kettlewell 2002]Section 1.2, "<stdio.h> and Character Types"
[NIST 2006]SAMATE Reference Dataset Test Case ID 000-000-088
[Summit 2005]Question 12.2