diff mbox series

[RFC,RFT,4/4] uio_hv_generic: Don't free decrypted memory

Message ID 20240222021006.2279329-5-rick.p.edgecombe@intel.com
State New
Headers
Series Handle set_memory_XXcrypted() errors in hyperv |

Commit Message

Edgecombe, Rick P Feb. 22, 2024, 2:10 a.m. UTC 
  On TDX it is possible for the untrusted host to cause
set_memory_encrypted() or set_memory_decrypted() to fail such that an
error is returned and the resulting memory is shared. Callers need to take
care to handle these errors to avoid returning decrypted (shared) memory to
the page allocator, which could lead to functional or security issues.

uio_hv_generic could free decrypted/shared pages if
set_memory_decrypted() fails.

Check the decrypted field in the gpadl before freeing in order to not
leak the memory.

Only compile tested.

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: linux-hyperv@vger.kernel.org
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 drivers/uio/uio_hv_generic.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

Comments

Michael Kelley March 1, 2024, 7:01 p.m. UTC | #1 
From: Rick Edgecombe <rick.p.edgecombe@intel.com> Sent: Wednesday, February 21, 2024 6:10 PM
> 
> On TDX it is possible for the untrusted host to cause

Same comment about TDX vs. CoCo VM.

> set_memory_encrypted() or set_memory_decrypted() to fail such that an
> error is returned and the resulting memory is shared. Callers need to take
> care to handle these errors to avoid returning decrypted (shared) memory to
> the page allocator, which could lead to functional or security issues.
> 
> uio_hv_generic could free decrypted/shared pages if
> set_memory_decrypted() fails.
> 
> Check the decrypted field in the gpadl before freeing in order to not
> leak the memory.
> 
> Only compile tested.
> 
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Wei Liu <wei.liu@kernel.org>
> Cc: Dexuan Cui <decui@microsoft.com>
> Cc: linux-hyperv@vger.kernel.org
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> ---
>  drivers/uio/uio_hv_generic.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
> index 20d9762331bd..6be3462b109f 100644
> --- a/drivers/uio/uio_hv_generic.c
> +++ b/drivers/uio/uio_hv_generic.c
> @@ -181,12 +181,14 @@ hv_uio_cleanup(struct hv_device *dev, struct
> hv_uio_private_data *pdata)
>  {
>  	if (pdata->send_gpadl.gpadl_handle) {
>  		vmbus_teardown_gpadl(dev->channel, &pdata->send_gpadl);
> -		vfree(pdata->send_buf);
> +		if (!pdata->send_gpadl.decrypted)
> +			vfree(pdata->send_buf);
>  	}
> 
>  	if (pdata->recv_gpadl.gpadl_handle) {
>  		vmbus_teardown_gpadl(dev->channel, &pdata->recv_gpadl);
> -		vfree(pdata->recv_buf);
> +		if (!pdata->recv_gpadl.decrypted)
> +			vfree(pdata->recv_buf);
>  	}
>  }
> 
> @@ -295,7 +297,8 @@ hv_uio_probe(struct hv_device *dev,
>  	ret = vmbus_establish_gpadl(channel, pdata->recv_buf,
>  				    RECV_BUFFER_SIZE, &pdata->recv_gpadl);
>  	if (ret) {
> -		vfree(pdata->recv_buf);
> +		if (!pdata->recv_gpadl.decrypted)
> +			vfree(pdata->recv_buf);
>  		goto fail_close;
>  	}
> 
> @@ -317,7 +320,8 @@ hv_uio_probe(struct hv_device *dev,
>  	ret = vmbus_establish_gpadl(channel, pdata->send_buf,
>  				    SEND_BUFFER_SIZE, &pdata->send_gpadl);
>  	if (ret) {
> -		vfree(pdata->send_buf);
> +		if (!pdata->send_gpadl.decrypted)
> +			vfree(pdata->send_buf);
>  		goto fail_close;
>  	}
> 
> --
> 2.34.1
diff mbox series

Patch

diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
index 20d9762331bd..6be3462b109f 100644
--- a/drivers/uio/uio_hv_generic.c
+++ b/drivers/uio/uio_hv_generic.c
@@ -181,12 +181,14 @@  hv_uio_cleanup(struct hv_device *dev, struct hv_uio_private_data *pdata)
 {
 	if (pdata->send_gpadl.gpadl_handle) {
 		vmbus_teardown_gpadl(dev->channel, &pdata->send_gpadl);
-		vfree(pdata->send_buf);
+		if (!pdata->send_gpadl.decrypted)
+			vfree(pdata->send_buf);
 	}
 
 	if (pdata->recv_gpadl.gpadl_handle) {
 		vmbus_teardown_gpadl(dev->channel, &pdata->recv_gpadl);
-		vfree(pdata->recv_buf);
+		if (!pdata->recv_gpadl.decrypted)
+			vfree(pdata->recv_buf);
 	}
 }
 
@@ -295,7 +297,8 @@  hv_uio_probe(struct hv_device *dev,
 	ret = vmbus_establish_gpadl(channel, pdata->recv_buf,
 				    RECV_BUFFER_SIZE, &pdata->recv_gpadl);
 	if (ret) {
-		vfree(pdata->recv_buf);
+		if (!pdata->recv_gpadl.decrypted)
+			vfree(pdata->recv_buf);
 		goto fail_close;
 	}
 
@@ -317,7 +320,8 @@  hv_uio_probe(struct hv_device *dev,
 	ret = vmbus_establish_gpadl(channel, pdata->send_buf,
 				    SEND_BUFFER_SIZE, &pdata->send_gpadl);
 	if (ret) {
-		vfree(pdata->send_buf);
+		if (!pdata->send_gpadl.decrypted)
+			vfree(pdata->send_buf);
 		goto fail_close;
 	}