Re: [LTP] [PATCH] mprotect04: fix powerpc crash when copying exec_func

[Cyril H. <ch...@su...>]

Hi!
> > > I'm seeing this on RHEL6.7 kernel, I haven't tried latest upstream yet.
> > 
> > Ah, you are right, the memory is not touched in the write_null()
> > function at all.
> 
> Right, I got confused by "access_ok(VERIFY_READ, buf, count)"
> in vfs_write(), but after reading code and comments it's clear it
> only checks if range _may_ be valid:
>  * access_ok: - Checks if a user space pointer is valid
>  ...
>  * Returns true (nonzero) if the memory block may be valid, false (zero)
>  * if it is definitely invalid.
>  *
>  * Note that, depending on architecture, this function probably just
>  * checks that the pointer is in the user space range - after calling
>  * this function, memory access functions may still return -EFAULT.

I do not have further questions. Acked.

-- 
Cyril Hrubis
ch...@su...