KVM: x86: Shrink the usercopy region of the emulation context
Shuffle a few operand structs to the end of struct x86_emulate_ctxt and
update the cache creation to whitelist only the region of the emulation
context that is expected to be copied to/from user memory, e.g. the
instruction operands, registers, and fetch/io/mem caches.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f558990..a69f7bf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -235,13 +235,13 @@ static struct kmem_cache *x86_emulator_cache;
static struct kmem_cache *kvm_alloc_emulator_cache(void)
{
- return kmem_cache_create_usercopy("x86_emulator",
- sizeof(struct x86_emulate_ctxt),
+ unsigned int useroffset = offsetof(struct x86_emulate_ctxt, src);
+ unsigned int size = sizeof(struct x86_emulate_ctxt);
+
+ return kmem_cache_create_usercopy("x86_emulator", size,
__alignof__(struct x86_emulate_ctxt),
- SLAB_ACCOUNT,
- 0,
- sizeof(struct x86_emulate_ctxt),
- NULL);
+ SLAB_ACCOUNT, useroffset,
+ size - useroffset, NULL);
}
static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt);