Messages in this thread | | | Subject | Re: [patch 1/3] flex_array: fix get function for elements in base starting at non-zero | From | Dave Hansen <> | Date | Tue, 18 Aug 2009 09:03:06 -0700 |
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On Mon, 2009-08-17 at 16:46 -0700, David Rientjes wrote: > If all array elements fit into the base structure and data is copied > using flex_array_put() starting at a non-zero index, flex_array_get() > will fail to return the data. > > This fixes the bug by only checking for NULL parts when all elements do > not fit in the base structure when flex_array_get() is used. Otherwise, > fa_element_to_part_nr() will always be 0 since there are no parts > structures needed and such element may never have been put. Thus, it > will remain NULL due to the kzalloc() of the base. > > Additionally, flex_array_put() now only checks for a NULL part when all > elements do not fit in the base structure. This is otherwise unnecessary > since the base structure is guaranteed to exist (or we would have already > hit a NULL pointer). > > Cc: Dave Hansen <dave@linux.vnet.ibm.com> > Signed-off-by: David Rientjes <rientjes@google.com> > --- > lib/flex_array.c | 14 ++++++++------ > 1 files changed, 8 insertions(+), 6 deletions(-) > > diff --git a/lib/flex_array.c b/lib/flex_array.c > --- a/lib/flex_array.c > +++ b/lib/flex_array.c > @@ -198,10 +198,11 @@ int flex_array_put(struct flex_array *fa, int element_nr, void *src, gfp_t flags > return -ENOSPC; > if (elements_fit_in_base(fa)) > part = (struct flex_array_part *)&fa->parts[0]; > - else > + else { > part = __fa_get_part(fa, part_nr, flags); > - if (!part) > - return -ENOMEM; > + if (!part) > + return -ENOMEM; > + } > dst = &part->elements[index_inside_part(fa, element_nr)]; > memcpy(dst, src, fa->element_size); > return 0; > @@ -257,11 +258,12 @@ void *flex_array_get(struct flex_array *fa, int element_nr) > > if (element_nr >= fa->total_nr_elements) > return NULL; > - if (!fa->parts[part_nr]) > - return NULL; > if (elements_fit_in_base(fa)) > part = (struct flex_array_part *)&fa->parts[0]; > - else > + else { > part = fa->parts[part_nr]; > + if (!part) > + return NULL; > + } > return &part->elements[index_inside_part(fa, element_nr)]; > }
This is fine with me, and fixes the bug you describe.
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Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
-- Dave
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