/sdl (Enable Additional Security Checks)

Enables recommended Security Development Lifecycle (SDL) checks. These checks change security-relevant warnings into errors, and set additional secure code-generation features.




/sdl enables a superset of the baseline security checks provided by /GS and overrides /GS-. By default, /sdl is off. /sdl- disables the additional security checks.

Compile-time Checks

/sdl enables these warnings as errors:

Warning enabled by /sdl Equivalent command-line switch Description
C4146 /we4146 A unary minus operator was applied to an unsigned type, resulting in an unsigned result.
C4308 /we4308 A negative integral constant converted to unsigned type, resulting in a possibly meaningless result.
C4532 /we4532 Use of continue, break, or goto keywords in a __finally/finally block has undefined behavior during abnormal termination.
C4533 /we4533 Code initializing a variable will not be executed.
C4700 /we4700 Use of an uninitialized local variable.
C4703 /we4703 Use of a potentially uninitialized local pointer variable.
C4789 /we4789 Buffer overrun when specific C run-time (CRT) functions are used.
C4995 /we4995 Use of a function marked with pragma deprecated.
C4996 /we4996 Use of a function marked as deprecated.

Runtime checks

When /sdl is enabled, the compiler generates code that does these checks at run time:

  • Enables the strict mode of /GS run-time buffer overrun detection, equivalent to compiling with #pragma strict_gs_check(push, on).

  • Does limited pointer sanitization. In expressions that don't involve dereferences and in types that have no user-defined destructor, pointer references are set to a non-valid address after a call to delete. This sanitization helps to prevent the reuse of stale pointer references.

  • Initializes class member pointers. Automatically initializes class members of pointer type to nullptr on object instantiation (before the constructor runs). It helps prevent the use of uninitialized pointers that the constructor doesn't explicitly initialize. The compiler-generated member pointer initialization is called as long as:

    • The object isn't allocated using a custom (user defined) operator new

    • The object isn't allocated as part of an array (for example new A[x])

    • The class isn't managed or imported

    • The class has a user-defined default constructor.

    To be initialized by the compiler-generated class initialization function, a member must be a pointer, and not a property or constant.

For more information, see Warnings, /sdl, and improving uninitialized variable detection.

To set this compiler option in the Visual Studio development environment

  1. Open the project's Property Pages dialog box. For details, see Set C++ compiler and build properties in Visual Studio.

  2. Select the Configuration Properties > C/C++ > General property page.

  3. Set the SDL checks property by using the property drop-down control. Choose OK or Apply to save your changes.

See also

MSVC Compiler Options
MSVC Compiler Command-Line Syntax