Messages in this thread | | | Subject | Re: [PATCH v2 1/2] of: overlay: Fix memory leak in of_overlay_apply() error path | From | Frank Rowand <> | Date | Mon, 4 Dec 2017 21:07:25 -0500 |
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Hi Geert,
Thanks for finding the issues and for the fixes.
Comments in line.
On 12/04/17 10:47, Geert Uytterhoeven wrote: > If of_resolve_phandles() fails, free_overlay_changeset() is called in > the error path. However, that function returns early if the list hasn't > been initialized yet, before freeing the object. > > Explicitly calling kfree() instead would solve that issue. However, that > complicates matter, by having to consider which of two different methods > to use to dispose of the same object. > > Hence make free_overlay_changeset() consider initialization state of the > different parts of the object, making it always safe to call (once!) to > dispose of a (partially) initialized overlay_changeset: > - Only destroy the changeset if the list was initialized, > - Ignore uninitialized IDs (zero). > > Reported-by: Colin King <colin.king@canonical.com> > Fixes: f948d6d8b792bb90 ("of: overlay: avoid race condition between applying multiple overlays") > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > drivers/of/overlay.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c > index 3b7a3980ff50d6bf..312cd658bec0083b 100644 > --- a/drivers/of/overlay.c > +++ b/drivers/of/overlay.c > @@ -630,11 +630,10 @@ static void free_overlay_changeset(struct overlay_changeset *ovcs) > { > int i; > > - if (!ovcs->cset.entries.next) > - return; > - of_changeset_destroy(&ovcs->cset); > + if (ovcs->cset.entries.next) > + of_changeset_destroy(&ovcs->cset); >
OK
> - if (ovcs->id) > + if (ovcs->id > 0)
Instead of this change, could you please make a change in init_overlay_changeset()?
Current init_overlay_changeset():
ovcs->id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL); if (ovcs->id <= 0) return ovcs->id;
My proposed version:
ret = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL); if (ret <= 0) return ret; ovcs->id = ret;
> idr_remove(&ovcs_idr, ovcs->id); > > for (i = 0; i < ovcs->count; i++) { >
Also, the previous version of the patch, and the discussion around the resulting bug make me think that I should not have moved 'kfree(ovcs)' into free_overlay_changeset(), because that kfree is then not very visible in the error path of of_overlay_apply(). Could you remove 'kfree(ovcs)' from free_overlay_changeset(), and instead call it immediately after each call to free_overlay_changeset()?
-Frank
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