[PATCH 5.13 045/223] KVM: SVM: Fix sev_pin_memory() error checks in SEV migration utilities

[Greg Kroah-Hartman]

From: Sean Christopherson <seanjc@xxxxxxxxxx>

[ Upstream commit c7a1b2b678c54ac19320daf525038d0e2e43ca7c ]

Use IS_ERR() instead of checking for a NULL pointer when querying for
sev_pin_memory() failures.  sev_pin_memory() always returns an error code
cast to a pointer, or a valid pointer; it never returns NULL.

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")
Fixes: 15fb7de1a7f5 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210506175826.2166383-3-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/x86/kvm/svm/sev.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 3dc3e2897804..02d60d7f903d 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1271,8 +1271,8 @@ static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	/* Pin guest memory */
 	guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
 				    PAGE_SIZE, &n, 0);
-	if (!guest_page)
-		return -EFAULT;
+	if (IS_ERR(guest_page))
+		return PTR_ERR(guest_page);
 
 	/* allocate memory for header and transport buffer */
 	ret = -ENOMEM;
@@ -1463,11 +1463,12 @@ static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	data.trans_len = params.trans_len;
 
 	/* Pin guest memory */
-	ret = -EFAULT;
 	guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
 				    PAGE_SIZE, &n, 0);
-	if (!guest_page)
+	if (IS_ERR(guest_page)) {
+		ret = PTR_ERR(guest_page);
 		goto e_free_trans;
+	}
 
 	/* The RECEIVE_UPDATE_DATA command requires C-bit to be always set. */
 	data.guest_address = (page_to_pfn(guest_page[0]) << PAGE_SHIFT) + offset;
-- 
2.30.2