linux-kernel - Re: [PATCH v3] x86/hyper-v: Mark TLFS structures packed

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 for Android: free password hash cracker in your pocket

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

Date:   Wed, 12 Dec 2018 18:43:23 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        linux-kernel@...r.kernel.org, Roman Kagan <rkagan@...tuozzo.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>, x86@...nel.org,
        "Michael Kelley \(EOSG\)" <Michael.H.Kelley@...rosoft.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3] x86/hyper-v: Mark TLFS structures packed

Vitaly Kuznetsov <vkuznets@...hat.com> writes:

>  /* Define virtual processor assist page structure. */
>  struct hv_vp_assist_page {
> @@ -519,7 +519,7 @@ struct hv_vp_assist_page {
>  	__u64 nested_enlightenments_control[2];
>  	__u32 enlighten_vmentry;
>  	__u64 current_nested_vmcs;
> -};
> +} __packed;
>  

This particular structure wasn't properly padded: u32 padding is missing
between 'enlighten_vmentry' and 'current_nested_vmcs'.

>  struct hv_enlightened_vmcs {
>  	u32 revision_id;
> @@ -693,7 +693,7 @@ struct hv_enlightened_vmcs {
>  		u32 nested_flush_hypercall:1;
>  		u32 msr_bitmap:1;
>  		u32 reserved:30;
> -	} hv_enlightenments_control;
> +	}  __packed hv_enlightenments_control;
>  	u32 hv_vp_id;
>  
>  	u64 hv_vm_id;
> @@ -703,7 +703,7 @@ struct hv_enlightened_vmcs {
>  	u64 padding64_5[7];
>  	u64 xss_exit_bitmap;
>  	u64 padding64_6[7];
> -};
> +} __packed;

struct hv_enlightened_vmcs also has a hole: we need an u16 padding after
'u16 host_tr_selector'.

Both these problems led to Enlightened VMCS for Hyper-V on KVM being
completely broken.

As this is not yet merged, v4 is coming to rescue!

-- 
Vitaly