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Bug 545

Summary: joystick: potential NULL pointer dereference
Product: SDL Reporter: Patrice Mandin <patmandin>
Component: joystickAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: 1.2.13   
Hardware: All   
OS: All   
Attachments: There's no reason to analyze what the NULL-pointer is pointing to, so we want to return.

Description Patrice Mandin 2008-02-01 09:38:00 UTC 
Around lines 140-150 in src/joystick/SDL_joystick.c:
--8<--
if ( ((joystick->naxes > 0) && !joystick->axes)
  || ((joystick->nhats > 0) && !joystick->hats)
  || ((joystick->nballs > 0) && !joystick->balls)
  || ((joystick->nbuttons > 0) && !joystick->buttons)) {
	SDL_OutOfMemory();
	SDL_JoystickClose(joystick);
	joystick = NULL;
}
if ( joystick->axes ) {
	SDL_memset(joystick->axes, 0,
		joystick->naxes*sizeof(Sint16));
}
--8<--

joystick variable is set to NULL, however, the checks that follow may still dereference it in this case.
Comment 1 Trygve Vea 2008-07-07 09:54:41 UTC 
Created attachment 259 [details]
There's no reason to analyze what the NULL-pointer is pointing to, so we want to return.

I looked at the code, and as far as I can tell we should get a risk-free effect by returning immediatly instead of setting the pointer to NULL and continue the execution of the function.

Suggested patch attached.