Vulnerability? Bug? Missing check after xmalloc() in xstrdup().

[liupeiyu]

Hi,In lib/string.h line 
38,staticinlinechar*xstrdup(constchar*c){size_tl=strlen(c)+1;// xmalloc may 
fail, and z will be NULL. char*z=xmalloc(l);// write to a NULL pointer, crash. 
memcpy(z,c,l);returnz;}I think this is a vulnerability, and maybe we can fix it 
as 
following:staticinlinechar*xstrdup(constchar*c){size_tl=strlen(c)+1;char*z=xmalloc(l);
 if(z)  { memcpy(z,c,l);returnz;  } else return -1;}Thanks for any 
consideration!Peiyu Liu, NESA lab, Zhejiang University