[patch] KVM: SVM: prevent DBG_DECRYPT and DBG_ENCRYPT overflow

[patch] KVM: SVM: prevent DBG_DECRYPT and DBG_ENCRYPT overflow

[David Rientjes]

This ensures that the address and length provided to DBG_DECRYPT and
DBG_ENCRYPT do not cause an overflow.

At the same time, pass the actual number of pages pinned in memory to
sev_unpin_memory() as a cleanup.

Reported-by: Cfir Cohen <cfir@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
---
 arch/x86/kvm/svm.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6799,7 +6799,8 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 	struct page **src_p, **dst_p;
 	struct kvm_sev_dbg debug;
 	unsigned long n;
-	int ret, size;
+	unsigned int size;
+	int ret;
 
 	if (!sev_guest(kvm))
 		return -ENOTTY;
@@ -6807,6 +6808,11 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 	if (copy_from_user(&debug, (void __user *)(uintptr_t)argp->data, sizeof(debug)))
 		return -EFAULT;
 
+	if (!debug.len || debug.src_uaddr + debug.len < debug.src_uaddr)
+		return -EINVAL;
+	if (!debug.dst_uaddr)
+		return -EINVAL;
+
 	vaddr = debug.src_uaddr;
 	size = debug.len;
 	vaddr_end = vaddr + size;
@@ -6857,8 +6863,8 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 						     dst_vaddr,
 						     len, &argp->error);
 
-		sev_unpin_memory(kvm, src_p, 1);
-		sev_unpin_memory(kvm, dst_p, 1);
+		sev_unpin_memory(kvm, src_p, n);
+		sev_unpin_memory(kvm, dst_p, n);
 
 		if (ret)
 			goto err;

Re: [patch] KVM: SVM: prevent DBG_DECRYPT and DBG_ENCRYPT overflow

[Singh, Brijesh]

On 3/25/19 1:47 PM, David Rientjes wrote:
> This ensures that the address and length provided to DBG_DECRYPT and
> DBG_ENCRYPT do not cause an overflow.
> 
> At the same time, pass the actual number of pages pinned in memory to
> sev_unpin_memory() as a cleanup.
> 
> Reported-by: Cfir Cohen <cfir@google.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>   arch/x86/kvm/svm.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
> 


Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>

thanks

Re: [patch] KVM: SVM: prevent DBG_DECRYPT and DBG_ENCRYPT overflow

[David Rientjes]

On Thu, 28 Mar 2019, Singh, Brijesh wrote:

> > This ensures that the address and length provided to DBG_DECRYPT and
> > DBG_ENCRYPT do not cause an overflow.
> > 
> > At the same time, pass the actual number of pages pinned in memory to
> > sev_unpin_memory() as a cleanup.
> > 
> > Reported-by: Cfir Cohen <cfir@google.com>
> > Signed-off-by: David Rientjes <rientjes@google.com>
> > ---
> >   arch/x86/kvm/svm.c | 12 +++++++++---
> >   1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> 
> 
> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
> 
> thanks
> 

Paolo, Radim, I don't see this in kvm.git, is it ready to be staged?

Re: [patch] KVM: SVM: prevent DBG_DECRYPT and DBG_ENCRYPT overflow

[Paolo Bonzini]

On 25/03/19 19:47, David Rientjes wrote:
> This ensures that the address and length provided to DBG_DECRYPT and
> DBG_ENCRYPT do not cause an overflow.
> 
> At the same time, pass the actual number of pages pinned in memory to
> sev_unpin_memory() as a cleanup.
> 
> Reported-by: Cfir Cohen <cfir@google.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  arch/x86/kvm/svm.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6799,7 +6799,8 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
>  	struct page **src_p, **dst_p;
>  	struct kvm_sev_dbg debug;
>  	unsigned long n;
> -	int ret, size;
> +	unsigned int size;
> +	int ret;
>  
>  	if (!sev_guest(kvm))
>  		return -ENOTTY;
> @@ -6807,6 +6808,11 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
>  	if (copy_from_user(&debug, (void __user *)(uintptr_t)argp->data, sizeof(debug)))
>  		return -EFAULT;
>  
> +	if (!debug.len || debug.src_uaddr + debug.len < debug.src_uaddr)
> +		return -EINVAL;
> +	if (!debug.dst_uaddr)
> +		return -EINVAL;
> +
>  	vaddr = debug.src_uaddr;
>  	size = debug.len;
>  	vaddr_end = vaddr + size;
> @@ -6857,8 +6863,8 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
>  						     dst_vaddr,
>  						     len, &argp->error);
>  
> -		sev_unpin_memory(kvm, src_p, 1);
> -		sev_unpin_memory(kvm, dst_p, 1);
> +		sev_unpin_memory(kvm, src_p, n);
> +		sev_unpin_memory(kvm, dst_p, n);
>  
>  		if (ret)
>  			goto err;
> 

Queued, thanks.

Paolo