[PATCH 5.13 044/223] KVM: SVM: Return -EFAULT if copy_to_user() for SEV mig packet header fails

[Greg Kroah-Hartman]

From: Sean Christopherson <seanjc@xxxxxxxxxx>

[ Upstream commit b4a693924aab93f3747465b2261add46c82c3220 ]

Return -EFAULT if copy_to_user() fails; if accessing user memory faults,
copy_to_user() returns the number of bytes remaining, not an error code.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Steve Rutherford <srutherford@xxxxxxxxxx>
Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
Cc: Ashish Kalra <ashish.kalra@xxxxxxx>
Fixes: d3d1af85e2c7 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210506175826.2166383-2-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/x86/kvm/svm/sev.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 8d36f0c73071..3dc3e2897804 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1309,8 +1309,9 @@ static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	}
 
 	/* Copy packet header to userspace. */
-	ret = copy_to_user((void __user *)(uintptr_t)params.hdr_uaddr, hdr,
-				params.hdr_len);
+	if (copy_to_user((void __user *)(uintptr_t)params.hdr_uaddr, hdr,
+			 params.hdr_len))
+		ret = -EFAULT;
 
 e_free_trans_data:
 	kfree(trans_data);
-- 
2.30.2