Re: [PATCH] KVM: x86: Account for 32-bit kernels when handling address in TSC attrs

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On 11/10/21 16:35, Oliver Upton wrote:
On Thu, Oct 7, 2021 at 6:16 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:

When handling TSC attributes, cast the userspace provided virtual address
to an unsigned long before casting it to a pointer to fix warnings on
32-bit kernels due to casting a 64-bit integer to a 32-bit pointer.

Add a check that the truncated address matches the original address, e.g.
to prevent userspace specifying garbage in bits 63:32.

   arch/x86/kvm/x86.c: In function ‘kvm_arch_tsc_get_attr’:
   arch/x86/kvm/x86.c:4947:22: error: cast to pointer from integer of different size
    4947 |  u64 __user *uaddr = (u64 __user *)attr->addr;
         |                      ^
   arch/x86/kvm/x86.c: In function ‘kvm_arch_tsc_set_attr’:
   arch/x86/kvm/x86.c:4967:22: error: cast to pointer from integer of different size
    4967 |  u64 __user *uaddr = (u64 __user *)attr->addr;
         |                      ^

Cc: Oliver Upton <oupton@xxxxxxxxxx>
Fixes: 469fde25e680 ("KVM: x86: Expose TSC offset controls to userspace")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
  arch/x86/kvm/x86.c | 10 ++++++++--
  1 file changed, 8 insertions(+), 2 deletions(-)


Reviewed-by: Oliver Upton <oupton@xxxxxxxxxx>


Squashed, thanks.

Paolo




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