[PATCH][BZ #13724] Do not segfault in pthread_setname_np (x, NULL)

[Rich Felker]

On Thu, Oct 03, 2013 at 02:20:09PM +0200, Ondřej Bílka wrote:
> Hi, this is another bug that could be handled quickly. Problem is if 
> pthread_setname_np (x, NULL) should return error code or segfault. 
> (see https://sourceware.org/bugzilla/show_bug.cgi?id=13724 )
> If first is desired then following patch does it. If we choose for
> second then close that bugzilla entry.
> 
> 	* sysdeps/unix/sysv/linux/pthread_setname.c (pthread_setname_np):
> 	Handle null.
> 
> diff --git a/nptl/sysdeps/unix/sysv/linux/pthread_setname.c b/nptl/sysdeps/unix/sysv/linux/pthread_setname.c
> index d6455dd..45eefa0 100644
> --- a/nptl/sysdeps/unix/sysv/linux/pthread_setname.c
> +++ b/nptl/sysdeps/unix/sysv/linux/pthread_setname.c
> @@ -34,6 +34,10 @@ pthread_setname_np (th, name)
>  {
>    const struct pthread *pd = (const struct pthread *) th;
>  
> +  /* Return EFAULT like pthread_getname_np(x, NULL, 16) does.  */
> +  if (name == NULL)
> +    return EFAULT;
> +

Why? I see no reason it "should" do this. Passing an invalid pointer
produces undefined behavior unless the behavior is documented as doing
something useful.

Rich