Astrée: standards compliance

Astrée is a sound static analyzer of C source code. Its primary purpose is proving the absence of runtime errors. This in­cludes viola­tions of the C99 standard and implementation-specific undefined be­haviors.

However, Astrée’s sophisticated analysis engine can also be applied to address other program properties relevant to functional safety and security, and to check for viola­tions of user-specified programming guide­lines.

This page offers a quick overview of how Astrée supports and checks for the C99 standard, the Common Weak­ness Enumer­ation (CWE) catalog, the SEI CERT C Coding Standard, the ISO/IEC guide­lines, and the MISRA C rules.


Annex J of ISO/IEC 9899:1999 (E) covers behaviors the standard regards as unspecified, undefined or implementation-defined, listing in three sections hundreds of scenarios in total.

A 34-page PDF description of how Astrée addresses each of these scenarios is available. For each section of Annex J, the document lists all the covered situations and provides details about how each is handled by Astrée.

Preview of the C99 compliance document

If you have Astrée installed, you can access the document via “Help” → “C compliance matrices”. Otherwise, contact to request a free copy.

Common Weakness Enumeration (CWE)

Below is the list of supported CWE rules as of Astrée 18.04. This includes items with the CWE CCR accuracies Exact, CWE-more-abstract, and CWE-more-specific. Items with the accuracy CWE-partial are grayed out. For further details, see Astrée’s “Help”  menu or contact

Astrée is sound, in that if a message or alarm is relevant for a given program, it will be reported by the tool.

118Improper access of indexable resource
119Improper restriction of operations within the bounds of a memory buffer
120Buffer copy without checking size of input (‘classic buffer overflow‘)
121Stack-based buffer overflow
122Heap-based buffer overflow
123Write-what-where condition
124Buffer underwrite
125Out-of-bounds read
126Buffer over-read
127Buffer under-read
128Wrap-around error
129Improper validation of array index
130Improper handling of length parameter inconsistency
131Incorrect calculation of buffer size
170Improper null termination
188Reliance on data/memory layout
190Integer overflow or wraparound
191Integer underflow or wraparound
193Off-by-one error
194Unexpected sign extension
195Signed to unsigned conversion error
196Unsigned to signed conversion error
197Numeric truncation error
240Improper handling of inconsistent structural elements
242Use of inherently dangerous function
252Unchecked return value
253Incorrect check of function return value
362Concurrent execution using shared resource
with improper synchronization (‘race condition’)
364Signal handler race condition
365Race condition in switch
366Race condition within a thread
367Time-of-check time-of-use (TOCTOU) race condition
369Divde by zero
398Indicator of poor code quality
404Improper resource shutdown or release
411Resource locking problems
415Double free
416Use after free
456Missing initialization of a variable
457Use of uninitialized variable
466Return of pointer value outside of expected range
471Modification of assumed-immutable data (MAID)
475Undefined behavior for input to API
476NULL pointer dereference
478Missing default case in switch statement
561Dead code
567Unsynchronized access to shared data in a multithreaded context
573Improper following of specification by caller
587Assignment of a fixed address to a pointer
588Attempt to access child of a nonstructure pointer
628Function call with incorrectly specified arguments
662Improper synchronization
665Improper initialization
667Improper locking
672Operation on a resource after expiration or release
680Integer overflow to buffer overflow
681Incorrect conversion between numeric types
682Incorrect calculation
685Function call with incorrect number of arguments
686Function call with incorrect argument type
690Unchecked return value to NULL pointer dereference
754Improper check for unusual or exceptional conditions
761Free of pointer not at start of buffer
763Release of invalid pointer or reference
764Multiple locks of a critical resource
765Multiple unlocks of a critical resource
785Use of path manipulation function without maximum-sized buffer
786Access of memory location before start of buffer
787Out-of-bounds write
805Buffer access with incorrect length value
806Buffer access using size of source buffer
823Use of out-of-range pointer offset
824Access of uninitialized pointer
825Expired pointer dereference
832Unlock of a resource that is not locked
835Loop with unreachable exit condition (‘infinite loop’)
908Use of uninitialized resource

SEI CERT C Coding Standard

Below is the list of SEI CERT rules and recommendations supported as of Astrée 18.04. The grayed-out items are supported partially. Exclamation marks denote recommendations that, by definition, cannot be checked for automatically by any tool. Further details are available via Astrée’s “Help”  menu or by contacting

Rule 01: Preprocessor
PRE32-C Do not use preprocessor directives in invocations of function-like macros
Rule 02: Declarations and initialization
DCL30-C Declare objects with appropriate storage durations
DCL31-C Declare identifiers before using them
DCL36-C Do not declare an identifier with conflicting linkage classifications
DCL37-C Do not declare or define a reserved identifier
DCL38-C Use the correct syntax when declaring a flexible array member
DCL40-C Do not create incompatible declarations of the same function or object
DCL41-C Do not declare variables inside a switch statement before the first case label
Rule 03: Expressions
EXP30-C Do not depend on the order of evaluation for side effects
EXP32-C Do not access a volatile object through a nonvolatile reference
EXP33-C Do not read uninitialized memory
EXP34-C Do not dereference null pointers
EXP36-C Do not cast pointers into more strictly aligned pointer types
EXP37-C Call functions with the correct number and type of arguments
EXP43-C Avoid undefined behavior when using restrict-qualified pointers
EXP44-C Do not rely on side effects in operands to sizeof, _Alignof, or _Generic
EXP45-C Do not perform assignments in selection statements
EXP46-C Do not use a bitwise operator with a Boolean-like operand
Rule 04: Integers
INT30-C Ensure that unsigned integer operations do not wrap
INT31-C Ensure that integer conversions do not result in lost or misinterpreted data
INT32-C Ensure that operations on signed integers do not result in overflow
INT33-C Ensure that division and remainder operations do not result in divide-by-zero errors
INT34-C Do not shift an expression by a negative number of bits
or by greater than or equal to the number of bits that exist in the operand
INT36-C Converting a pointer to integer or integer to pointer
Rule 05: Floating point
FLP30-C Do not use floating-point variables as loop counters
FLP34-C Ensure that floating-point conversions are within range of the new type
Rule 06: Arrays
ARR30-C Do not form or use out-of-bounds pointers or array subscripts
ARR36-C Do not subtract or compare two pointers that do not refer to the same array
ARR37-C Do not add or subtract an integer to a pointer to a non-array object
Rule 07: Characters and strings
STR30-C Do not attempt to modify string literals
STR31-C Guarantee that storage for strings has sufficient space
for character data and the null terminator
STR32-C Do not pass a non-null-terminated character sequence
to a library function that expects a string
STR37-C Arguments to character-handling functions must be
representable as an unsigned char
Rule 08: Memory management
MEM30-C Do not access freed memory
MEM31-C Free dynamically allocated memory when no longer needed
MEM34-C Only free memory allocated dynamically
MEM35-C Allocate sufficient memory for an object
Rule 09: Input/output
FIO37-C Do not assume that fgets() or fgetws()
returns a nonempty string when successful
FIO38-C Do not copy a FILE object
Rule 10: Environment
ENV33-C Do not call system()
Rule 11: Signals
SIG30-C Call only asynchronous-safe functions within signal handlers
SIG31-C Do not access shared objects in signal handlers
SIG34-C Do not call signal() from within interruptible signal handlers
Rule 12: Error handling
ERR33-C Detect and handle standard library errors
Rule 14: Concurrency
CON32-C Prevent data races when accessing bit-fields from multiple threads
CON33-C Avoid race conditions when using library functions
CON37-C Do not call signal() in a multithreaded program
Rule 48: Miscellaneous
MSC30-C Do not use the rand() function for generating pseudorandom numbers
MSC37-C Ensure that control never reaches the end of a non-void function
Recommendation 01: Preprocessor
PRE00-C Prefer inline or static functions to function-like macros
PRE01-C Use parentheses within macros around parameter names
PRE05-C Understand macro replacement when concatenating tokens
or performing stringification
PRE06-C Enclose header files in an inclusion guard
PRE07-C Avoid using repeated question marks
Recommendation 02: Declarations and initialization
DCL00-C Const-qualify immutable objects
DCL01-C Do not reuse variable names in subscopes
DCL07-C Include the appropriate type information in function declarators
DCL08-C Properly encode relationships in constant definitions !
DCL10-C Maintain the contract between the writer and caller of variadic functions
DCL11-C Understand the type issues associated with variadic functions !
DCL13-C Declare function parameters that are pointers to values not changed by the function as const
DCL15-C Declare file-scope objects or functions that do not need external linkage as static
DCL16-C Use L, not l, to indicate a long value
DCL17-C Beware of miscompiled volatile-qualified variables !
DCL18-C Do not begin integer constants with 0 when specifying a decimal value
DCL19-C Minimize the scope of variables and functions
DCL20-C Explicitly specify void when a function accepts no arguments
DCL21-C Understand the storage of compound literals !
DCL22-C Use volatile for data that cannot be cached !
DCL23-C Guarantee that mutually visible identifiers are unique
Recommendation 03: Expressions
EXP02-C Be aware of the short-circuit behavior of the logical AND and OR operators
EXP03-C Do not assume the size of a structure is the sum of the sizes of its members
EXP08-C Ensure pointer arithmetic is used correctly
EXP10-C Do not depend on the order of evaluation of subexpressions
or the order in which side effects take place
EXP12-C Do not ignore values returned by functions
EXP19-C Use braces for the body of an if, for, or while statement
EXP20-C Perform explicit tests to determine success, true and false, and equality
Recommendation 04: Integers
INT00-C Understand the data model used by your implementation(s) !
INT02-C Understand integer conversion rules !
INT07-C Use only explicitly signed or unsigned char type for numeric values
INT08-C Verify that all integer values are in range
INT09-C Ensure enumeration constants map to unique values
INT12-C Do not make assumptions about the type of a plain int bit-field
when used in an expression
INT13-C Use bitwise operators only on unsigned operands
INT18-C Evaluate integer expressions in a larger size before comparing
or assigning to that size
Recommendation 05: Floating point
FLP00-C Understand the limitations of floating-point numbers !
FLP01-C Take care in rearranging floating-point expressions !
FLP02-C Avoid using floating-point numbers when precise computation is needed
FLP03-C Detect and handle floating-point errors
FLP04-C Check floating-point inputs for exceptional values
FLP06-C Convert integers to floating point for floating-point operations
Recommendation 06: Arrays
ARR00-C Understand how arrays work !
ARR02-C Explicitly specify array bounds, even if implicitly defined by an initializer
Recommendation 07: Characters and strings
STR00-C Represent characters using an appropriate type
STR04-C Use plain char for characters in the basic character set
STR09-C Don’t assume numeric values for expressions with type plain character
STR11-C Do not specify the bound of a character array initialized with a string literal
Recommendation 08: Memory management
MEM01-C Store a new value in pointers immediately after free()
MEM04-C Beware of zero-length allocations
MEM07-C Ensure that the arguments to calloc(), when multiplied, do not wrap
Recommendation 09: Input/output
FIO14-C Understand the difference between text mode and binary mode with file streams !
Recommendation 11: Signals
SIG01-C Understand implementation-specific details regarding signal handler persistence !
Recommendation 12: Error handling
ERR06-C Understand the termination behavior of assert() and abort() !
Recommendation 14: Concurrency
CON00-C Avoid race conditions with multiple threads
CON01-C Acquire and release synchronization primitives in the same module,
at the same level of abstraction
CON03-C Ensure visibility when accessing shared variables
CON06-C Ensure that every mutex outlives the data it protects
Recommendation 15: Concurrency (POSIX)
CON00-C Avoid race conditions with multiple threads
Recommendation 48: Miscellaneous
MSC01-C Strive for logical completeness
MSC04-C Use comments consistently and in a readable fashion
MSC07-C Detect and remove dead code
MSC12-C Detect and remove code that has no effect or is never executed
MSC13-C Detect and remove unused values
MSC15-C Do not depend on undefined behavior
MSC17-C Finish every set of statements associated with a case label
with a break statement
MSC20-C Do not use a switch statement to transfer control into a complex block
MSC23-C Beware of vendor-specific library and language differences
MSC24-C Do not use deprecated or obsolescent functions
Recommendation 51: Microsoft Windows
WIN03-C Understand HANDLE inheritance !


RuleChecker screenshot

Astrée’s integrated RuleChecker supports both MISRA-C:2004 and MISRA-C:2012 (including Amendment 1). It is highly configurable, allowing you to check for individual rules and even specific aspects of certain rules.

To save time, the RuleChecker can also be invoked separately, without running a full-fledged Astrée analysis. However, semantical rules greatly benefit from running Astrée, as the soundness of its semantic analyses guarantees zero false negatives and minimizes false positives. This is where Astrée truly shines, as no competing MISRA checker currently on the market is capable of checking for these rules with such precision, and no testing environment can guarantee the full data and path coverage required.

As of Astrée 18.04, a total of 277 rules of the two rule sets are checked. An 11-page PDF description of how Astrée handles each rule is available on request. Contact for your free copy.

Below is just a quick overview of all the supported rule categories.

2Language extensions
4Character sets
8Declarations and definitions
10Arithmetic type conversions
11Pointer type conversions
13Control statement expressions
14Control flow
15Switch statements
17Pointers and arrays
18Structures and unions
19Preprocessing directives
20Standard libraries
21Run-time failures
1A standard C environment
2Unused code
4Character sets and lexical convention
7Literals and constants
8Declarations and definitions
10The essential type model
11Pointer type conversions
13Side effects
14Control statement expressions
15Control flow
16Switch statements
18Pointers and arrays
19Overlapping storage
20Preprocessing directives
21Standard libraries
MISRA-C:2012 Amendment 1
21Standard libraries
Checking C++ code is possible starting with the most recent release 18.04. A majority of MISRA C++:2008 rules are supported.

ISO/IEC TS 17961:2013

Below is the list of ISO/IEC TS 17961:2013 rules supported as of Astrée 18.04. The grayed-out rules are supported partially. Further details are available via Astrée’s “Help”  menu or by contacting

2Accessing freed memory
6Calling functions with incorrect arguments
10Converting a pointer to integer or integer to pointer
11Converting pointer values to more strictly aligned pointer types
12Copying a FILE object
13Declaring the same function or object in incompatible ways
14Dereferencing an out-of-domain pointer
15Escaping of the address of an automatic object
17Use of an implied default in a switch statement
21Allocating insufficient memory
22Forming or using out-of-bounds pointers or array subscripts
23Freeing memory multiple times
26Integer division errors
28Modifying string literals
29Modifying the string returned by getenv, localeconv, setlocale, and strerror
30Overflowing signed integers
34Reallocating or freeing memory that was not dynamically allocated
35Referencing uninitialized memory
36Subtracting or comparing two pointers that do not refer to the same array
38Taking the size of a pointer to determine the size of the pointed-to type
39Using a tainted value as an argument to an unprototyped function pointer
44Using identifiers that are reserved for the implementation
46Tainted, potentially mutilated, or out-of-domain integer values are used in a restricted sink