2019-03-25 18:48:29

by David Rientjes

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

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 <[email protected]>
Signed-off-by: David Rientjes <[email protected]>
---
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;

2019-03-28 13:59:01

by Brijesh Singh

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

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 <[email protected]>
> Signed-off-by: David Rientjes <[email protected]>
> ---
> arch/x86/kvm/svm.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>


Reviewed-by: Brijesh Singh <[email protected]>

thanks

2019-04-04 21:27:57

by David Rientjes

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

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 <[email protected]>
> > Signed-off-by: David Rientjes <[email protected]>
> > ---
> > arch/x86/kvm/svm.c | 12 +++++++++---
> > 1 file changed, 9 insertions(+), 3 deletions(-)
> >
>
>
> Reviewed-by: Brijesh Singh <[email protected]>
>
> thanks
>

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

2019-04-05 18:51:28

by Paolo Bonzini

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

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 <[email protected]>
> Signed-off-by: David Rientjes <[email protected]>
> ---
> 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