Re: [PATCH v3] powerpc: Do not make the entire heap executable

On 08/10/2016 12:43 AM, Kees Cook wrote:

quoted

-static int do_brk(unsigned long addr, unsigned long len)
+static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags)
 {
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma, *prev;
-       unsigned long flags;
        struct rb_node **rb_link, *rb_parent;
        pgoff_t pgoff = addr >> PAGE_SHIFT;
        int error;

@@ -2666,7 +2665,7 @@ static int do_brk(unsigned long addr, unsigned long len)
        if (!len)
                return 0;

-       flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
+       flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

For sanity's sake, should a mask be applied here? i.e. to be extra
careful about what flags can get passed in?

Maybe... I am leaving it to mm experts.

Otherwise, this looks okay to me:

Reviewed-by: Kees Cook <redacted>

-Kees