* [PATCH] vfio: Fix double free for caps->buf
@ 2022-06-28 5:07 Schspa Shi
2022-06-28 8:17 ` Cornelia Huck
0 siblings, 1 reply; 2+ messages in thread
From: Schspa Shi @ 2022-06-28 5:07 UTC (permalink / raw)
To: alex.williamson, cohuck; +Cc: kvm, linux-kernel, zhaohui.shi, Schspa Shi
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.
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;
caps->size = 0;
return ERR_PTR(-ENOMEM);
}
--
2.29.0
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] vfio: Fix double free for caps->buf
2022-06-28 5:07 [PATCH] vfio: Fix double free for caps->buf Schspa Shi
@ 2022-06-28 8:17 ` Cornelia Huck
0 siblings, 0 replies; 2+ messages in thread
From: Cornelia Huck @ 2022-06-28 8:17 UTC (permalink / raw)
To: Schspa Shi, alex.williamson; +Cc: kvm, linux-kernel, zhaohui.shi, Schspa Shi
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);
> }
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-06-28 5:07 [PATCH] vfio: Fix double free for caps->buf Schspa Shi
2022-06-28 8:17 ` Cornelia Huck
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