Commit 398180f9 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: TDX: Use struct_size to simplify tdx_get_capabilities() 



Use struct_size() instead of manually calculating the number of bytes to
allocate for 'caps', including the nested flexible array, and copy all of
'caps' to user space with a single copy_to_user() call (thanks to the full
size being provided by struct_size()).

Signed-off-by: default avatarThorsten Blum <thorsten.blum@linux.dev>
Tested-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Link: https://patch.msgid.link/20251017213914.167301-1-thorsten.blum@linux.dev


[sean: separate from swap of get_user() vs. kzalloc() ordering]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 11b79f83

arch/x86/kvm/vmx/tdx.c

+4 −9
Original line number Diff line number Diff line
@@ -2231,9 +2231,8 @@ static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd) 
	if (nr_user_entries < td_conf->num_cpuid_config)

		return -E2BIG;



	caps = kzalloc(sizeof(*caps) +

		       sizeof(struct kvm_cpuid_entry2) * td_conf->num_cpuid_config,

		       GFP_KERNEL);

	caps = kzalloc(struct_size(caps, cpuid.entries,

				   td_conf->num_cpuid_config), GFP_KERNEL);

	if (!caps)

		return -ENOMEM;
@@ -2241,16 +2240,12 @@ static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd) 
	if (ret)

		goto out;



	if (copy_to_user(user_caps, caps, sizeof(*caps))) {

	if (copy_to_user(user_caps, caps, struct_size(caps, cpuid.entries,

						      caps->cpuid.nent))) {

		ret = -EFAULT;

		goto out;

	}



	if (copy_to_user(user_caps->cpuid.entries, caps->cpuid.entries,

			 caps->cpuid.nent *

			 sizeof(caps->cpuid.entries[0])))

		ret = -EFAULT;



out:

	/* kfree() accepts NULL. */

	kfree(caps);