linux-kernel - Re: [PATCH v2 3/5] hv_netvsc: Don't free decrypted memory

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Mon, 11 Mar 2024 22:03:59 -0700
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: mhklinux@...look.com, rick.p.edgecombe@...el.com, kys@...rosoft.com,
 haiyangz@...rosoft.com, wei.liu@...nel.org, decui@...rosoft.com,
 gregkh@...uxfoundation.org, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, kirill.shutemov@...ux.intel.com,
 dave.hansen@...ux.intel.com, linux-kernel@...r.kernel.org,
 linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
 linux-coco@...ts.linux.dev
Cc: elena.reshetova@...el.com
Subject: Re: [PATCH v2 3/5] hv_netvsc: Don't free decrypted memory


On 3/11/24 9:15 AM, mhkelley58@...il.com wrote:
> From: Rick Edgecombe <rick.p.edgecombe@...el.com>
>
> In CoCo VMs 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.
>
> The netvsc driver could free decrypted/shared pages if
> set_memory_decrypted() fails. Check the decrypted field in the gpadl
> to decide whether to free the memory.
>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> Signed-off-by: Michael Kelley <mhklinux@...look.com>
> ---
LGTM

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>  drivers/net/hyperv/netvsc.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 82e9796c8f5e..70b7f91fb96b 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -154,8 +154,11 @@ static void free_netvsc_device(struct rcu_head *head)
>  	int i;
>  
>  	kfree(nvdev->extension);
> -	vfree(nvdev->recv_buf);
> -	vfree(nvdev->send_buf);
> +
> +	if (!nvdev->recv_buf_gpadl_handle.decrypted)
> +		vfree(nvdev->recv_buf);
> +	if (!nvdev->send_buf_gpadl_handle.decrypted)
> +		vfree(nvdev->send_buf);
>  	bitmap_free(nvdev->send_section_map);
>  
>  	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer