QA·C Help - 2846

	2846	Definite: Maximum number of characters to be written is larger than the target buffer size.

Arrays

A definite anomaly has been detected.

Certain standard library functions specify a maximum number (M) of characters to be written to a char array (A).

function	A parameter number	M parameter number
asctime_s	1	2
ctime_s	1	2
snprintf	1	2
snprintf_s	1	2
strcpy_s	1	2
strncat	1	3
strncat_s	1	2
strncat_s	1	4
strncat_s	3	4
strncpy	1	3
strncpy_s	1	4

This message is issued whenever a non constant expression is used for M and its value is always greater than the size of object A. This may result in an access outside the bounds of A.

For example:


/*PRQA S 1-9999 ++*/
/*PRQA S 2846 --*/

#include <string.h>

extern char a[10];
extern char b[11];

void foo (int m)
{
  if (m > sizeof (a))
  {
    strncpy (a, b, m);   /* 2846 */
  }
}

MISRA-C:2004 Rules applicable to message 2846:

Rule 21.1 (Required)

Minimisation of run-time failures shall be ensured by the use of at least one of (a) static analysis tools/techniques; (b) dynamic analysis tools/techniques; (c) explicit coding of checks to handle run-time faults

See also:

2845 Constant: Maximum number of characters to be written is larger than the target buffer size.
2847 Apparent: Maximum number of characters to be written is larger than the target buffer size.
2848 Suspicious: Maximum number of characters to be written is larger than the target buffer size.

QA·C Source Code Analyser 8.1
MISRA-C:2004 Compliance Module 3.2
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