hw/cxl: Mailbox input parser hardening against invalid input.

[PATCH qemu 02/10] hw/cxl: Check input includes at least the header in cmd_features_set_feature()

Posted by Jonathan Cameron via 3 weeks, 1 day ago

A buggy guest might write an insufficiently large message.
Check the header is present. Whilst zero data after the header is very
odd it will just result in failure to copy any data.

Reported-by: Esifiel <esifiel@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 hw/cxl/cxl-mailbox-utils.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 17924410dd..e63140aefe 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -1238,6 +1238,9 @@ static CXLRetCode cmd_features_set_feature(const struct cxl_cmd *cmd,
     CXLType3Dev *ct3d;
     uint16_t count;
 
+    if (len_in < sizeof(*hdr)) {
+        return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
+    }
 
     if (!object_dynamic_cast(OBJECT(cci->d), TYPE_CXL_TYPE3)) {
         return CXL_MBOX_UNSUPPORTED;
-- 
2.43.0

Re: [PATCH qemu 02/10] hw/cxl: Check input includes at least the header in cmd_features_set_feature()

Posted by Fan Ni 2 weeks, 3 days ago

On Fri, Nov 01, 2024 at 01:39:09PM +0000, Jonathan Cameron wrote:
> A buggy guest might write an insufficiently large message.
> Check the header is present. Whilst zero data after the header is very
> odd it will just result in failure to copy any data.
> 
> Reported-by: Esifiel <esifiel@gmail.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---

Reviewed-by: Fan Ni <fan.ni@samsung.com>

>  hw/cxl/cxl-mailbox-utils.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> index 17924410dd..e63140aefe 100644
> --- a/hw/cxl/cxl-mailbox-utils.c
> +++ b/hw/cxl/cxl-mailbox-utils.c
> @@ -1238,6 +1238,9 @@ static CXLRetCode cmd_features_set_feature(const struct cxl_cmd *cmd,
>      CXLType3Dev *ct3d;
>      uint16_t count;
>  
> +    if (len_in < sizeof(*hdr)) {
> +        return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
> +    }
>  
>      if (!object_dynamic_cast(OBJECT(cci->d), TYPE_CXL_TYPE3)) {
>          return CXL_MBOX_UNSUPPORTED;
> -- 
> 2.43.0
> 

-- 
Fan Ni