Nothing! /proc lived without this check for 30 years:
int proc_match(int len,const char * name,struct proc_dir_entry * de)
{
register int same __asm__("ax");
if (!de || !de->low_ino)
return 0;
/* "" means "." ---> so paths like "/usr/lib//libc.a" work */
if (!len && (de->name[0]=='.') && (de->name[1]=='\0'))
return 1;
if (de->namelen != len)
return 0;
__asm__("cld\n\t"
"repe ; cmpsb\n\t"
"setz %%al"
:"=a" (same)
:"0" (0),"S" ((long) name),"D" ((long) de->name),"c" (len)
:"cx","di","si");
return same;
}