[1/6] xen/gntdev: Fix dmabuf import with non-zero sgt offset
diff mbox series

Message ID 20200731125109.18666-2-andr2000@gmail.com
State New
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Series
  • Fixes and improvements for Xen pvdrm
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Commit Message

Oleksandr Andrushchenko July 31, 2020, 12:51 p.m. UTC
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

It is possible that the scatter-gather table during dmabuf import has
non-zero offset of the data, but user-space doesn't expect that.
Fix this by failing the import, so user-space doesn't access wrong data.

Fixes: 37ccb44d0b00 ("xen/gntdev: Implement dma-buf import functionality")

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
 drivers/xen/gntdev-dmabuf.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Juergen Gross Aug. 4, 2020, 6:11 a.m. UTC | #1
On 31.07.20 14:51, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> 
> It is possible that the scatter-gather table during dmabuf import has
> non-zero offset of the data, but user-space doesn't expect that.
> Fix this by failing the import, so user-space doesn't access wrong data.
> 
> Fixes: 37ccb44d0b00 ("xen/gntdev: Implement dma-buf import functionality")

I can't find this commit in the tree. Did you mean bf8dc55b1358?

And don't you want to Cc stable for this patch, too?

> 
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Acked-by: Juergen Gross <jgross@suse.com>


Juergen
Oleksandr Andrushchenko Aug. 4, 2020, 6:34 a.m. UTC | #2
On 8/4/20 9:11 AM, Jürgen Groß wrote:
> On 31.07.20 14:51, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>
>> It is possible that the scatter-gather table during dmabuf import has
>> non-zero offset of the data, but user-space doesn't expect that.
>> Fix this by failing the import, so user-space doesn't access wrong data.
>>
>> Fixes: 37ccb44d0b00 ("xen/gntdev: Implement dma-buf import functionality")
>
> I can't find this commit in the tree. Did you mean bf8dc55b1358?
I'll double-check, thank you
>
> And don't you want to Cc stable for this patch, too?
Hm, yes, sounds reasonable
>
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Acked-by: Juergen Gross <jgross@suse.com>
>
>
> Juergen

Patch
diff mbox series

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index 75d3bb948bf3..b1b6eebafd5d 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -613,6 +613,14 @@  dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 		goto fail_detach;
 	}
 
+	/* Check that we have zero offset. */
+	if (sgt->sgl->offset) {
+		ret = ERR_PTR(-EINVAL);
+		pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
+			 sgt->sgl->offset);
+		goto fail_unmap;
+	}
+
 	/* Check number of pages that imported buffer has. */
 	if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
 		ret = ERR_PTR(-EINVAL);