On Tue, 09 Dec 2008 09:03:19 -0600
Timur Tabi <[EMAIL PROTECTED]> wrote:
> Guillaume Knispel wrote:
> > There is an error in rh_alloc_fixed() of the Remote Heap code:
> > If there is at least one free block blk won't be NULL at the end of the
> > search loop, so -ENOMEM won't be returned and the else branch of
> > "if (bs == s || be == e)" will be taken, corrupting the management
> > structures.
> >
> > Signed-off-by: Guillaume Knispel <[EMAIL PROTECTED]>
> > ---
> > Fix an error in rh_alloc_fixed() that made allocations succeed when
> > they should fail, and corrupted management structures.
> >
> > diff --git a/arch/powerpc/lib/rheap.c b/arch/powerpc/lib/rheap.c
> > index 29b2941..45907c1 100644
> > --- a/arch/powerpc/lib/rheap.c
> > +++ b/arch/powerpc/lib/rheap.c
> > @@ -556,6 +556,7 @@ unsigned long rh_alloc_fixed(rh_info_t * info, unsigned
> > long start, int size, co
> > be = blk->start + blk->size;
> > if (s >= bs && e <= be)
> > break;
> > + blk = NULL;
> > }
> >
> > if (blk == NULL)
>
> This is a good catch, however, wouldn't it be better to do this:
>
> list_for_each(l, &info->free_list) {
> blk = list_entry(l, rh_block_t, list);
> /* The range must lie entirely inside one free block */
> bs = blk->start;
> be = blk->start + blk->size;
> if (s >= bs && e <= be)
> break;
> }
>
> - if (blk == NULL)
> + if (blk == &info->free_list)
> return (unsigned long) -ENOMEM;
>
> I haven't tested this, but the if-statement at the end of the loop is meant to
> check whether the list_for_each() loop got to the end or not.
>
> What do you think?
blk = NULL; at the end of the loop is what is done in the more used
rh_alloc_align(), so for consistency either we change both or we use
the same construction here.
I also think that testing for &info->free_list is harder to understand
because you must have the linked list implementation in your head
(which a kernel developer should anyway so this is not so important)
Guillaume Knispel
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