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The successful completion or failure of each of the standard library functions listed in the following table shall be determined either by comparing the function’s return value with the value listed in the column labeled “Error Return” or by calling one of the library functions mentioned in the footnotes to the same column.
Function | Successful Return | Error Return |
|
---|---|---|---|
| Pointer to a |
|
|
| Pointer to a |
|
|
|
| Nonzero | Unchanged |
Setting errno
is a POSIX [ISO/IEC 9945:2008] extension to the C Standard. On error, posix_memalign()
returns a value that corresponds to one of the constants defined in the <errno.h>
header. The function does not set errno
. The posix_memalign()
function is optional and is not required to be provided by POSIX-conforming implementations.
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Return values from the following functions do not need to be checked because their historical use has overwhelmingly omitted error checking, and the consequences are not relevant to security.
Function | Successful Return | Error Return |
---|---|---|
| Number of characters (nonnegative) | Negative |
| Character written |
|
| Nonnegative |
|
| Wide character written |
|
| Number of characters (nonnegative) | Negative |
| Number of wide characters (nonnegative) | Negative |
| Number of wide characters (nonnegative) | Negative |
Risk Assessment
Failing to detect error conditions can lead to unpredictable results, including abnormal program termination and denial-of-service attacks or, in some situations, could even allow an attacker to run arbitrary code.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
---|---|---|---|---|---|
POS54-C | High | Likely | Medium | P18 | L1 |
Automated Detection
Tool | Version | Checker | Description | ||||||
---|---|---|---|---|---|---|---|---|---|
CodeSonar |
| LANG.FUNCS.IRV | Ignored return value | ||||||
Compass/ROSE |
Can detect violations of this recommendation when checking for violations of EXP12-C. Do not ignore values returned by functions and EXP34-C. Do not dereference null pointers | |||||||||
| CHECKED_RETURN | Finds inconsistencies in how function call return values are handled. Coverity Prevent cannot discover all violations of this recommendation, so further verification is necessary | |||||||
Klocwork |
| SV.RVT.RETVAL_NOTTESTED |
LDRA tool suite |
| 80 D | Partially implemented | ||||||
Parasoft C/C++test |
|
|
| CODSTA-122_ |
a, CODSTA-122_b |
, BD-PB-NP | Partially implemented | ||||||||
PRQA QA-C |
| 3200 | Partially implemented |
Related Vulnerabilities
The vulnerability in Adobe Flash [VU#159523] arises because Flash neglects to check the return value from calloc()
. Even when calloc()
returns NULL
, Flash writes to an offset from the return value. Dereferencing NULL
usually results in a program crash, but dereferencing an offset from NULL
allows an exploit to succeed without crashing the program.
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Key here (explains table format and definitions)
Bibliography
[DHS 2006] | Handle All Errors Safely |
[Henricson 1997] | Recommendation 12.1, "Check for All Errors Reported from Functions" |
[ISO/IEC 9899:2011] | Subclause 7.21.7.10, "The ungetc Function" |
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