link(2) and EFAULT

Michael Galassi nerd at
Thu Jul 26 14:58:32 PDT 2007

>Simon Schubert <Simon> writes:
>> Like any other error: abort or do something else sensible.
>I was wondering what, if anything, would be sensible when
>receiving this error message. This seems like something a
>userland application should rarely get.

On the contrary, if you make a system call and pass a null pointer in
you are *very likely* to get exactly this errno value.

>Michael Galassi <nerd at> writes:
>> copyin() is called by the system call code and returns
>> efault after validating the address, before actually
>> touching it.
>Ah ha. So there's something getting corrupted somewhere. 
>Useful to know. Thanks. 

I've most often seen this with applications making system calls and
passing uninitialized pointers.  ymmv


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