Messages in this thread | | | From | Cornelia Huck <> | Subject | Re: [PATCH] vfio: Fix double free for caps->buf | Date | Tue, 28 Jun 2022 10:17:52 +0200 |
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On Tue, Jun 28 2022, Schspa Shi <schspa@gmail.com> wrote:
> There is a double free, if vfio_iommu_dma_avail_build_caps > calls failed. > > The following call path will call vfio_info_cap_add multiple times > > vfio_iommu_type1_get_info > if (!ret) > ret = vfio_iommu_dma_avail_build_caps(iommu, &caps); > > if (!ret) > ret = vfio_iommu_iova_build_caps(iommu, &caps); > > If krealloc failed on vfio_info_cap_add, there will be a double free.
But it will only call it several times if the last call didn't fail, won't it?
> > Signed-off-by: Schspa Shi <schspa@gmail.com> > --- > drivers/vfio/vfio.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > index 61e71c1154be..a0fb93866f61 100644 > --- a/drivers/vfio/vfio.c > +++ b/drivers/vfio/vfio.c > @@ -1812,6 +1812,7 @@ struct vfio_info_cap_header *vfio_info_cap_add(struct vfio_info_cap *caps, > buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL); > if (!buf) { > kfree(caps->buf); > + caps->buf = NULL;
We could add this as some kind of hardening, I guess. Current callers all seem to deal with failure correctly.
> caps->size = 0; > return ERR_PTR(-ENOMEM); > }
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