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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Jul 2025 20:41:47.7004 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 54e93ca0-0bde-42f1-af6c-08ddc4a92f49 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF000001F0.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ5PPFDF5E260D0 Content-Type: text/plain; charset="utf-8" Commit 7ffeb2fc2670 ("x86/sev: Document requirement for linear mapping of guest request buffers") added a check that requires the guest request buffers to be in the linear mapping. The get_derived_key() function was passing a buffer that was allocated on the stack, resulting in the call to snp_send_guest_request() returning an error. Update the get_derived_key() function to use an allocated buffer instead of a stack buffer. Fixes: 7ffeb2fc2670 ("x86/sev: Document requirement for linear mapping of g= uest request buffers") Signed-off-by: Tom Lendacky --- drivers/virt/coco/sev-guest/sev-guest.c | 27 +++++++++++-------------- 1 file changed, 12 insertions(+), 15 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index d2b3ae7113ab..b01ec99106cd 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -116,13 +116,11 @@ static int get_report(struct snp_guest_dev *snp_dev, = struct snp_guest_request_io =20 static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest= _request_ioctl *arg) { + struct snp_derived_key_resp *derived_key_resp __free(kfree) =3D NULL; struct snp_derived_key_req *derived_key_req __free(kfree) =3D NULL; - struct snp_derived_key_resp derived_key_resp =3D {0}; struct snp_msg_desc *mdesc =3D snp_dev->msg_desc; struct snp_guest_req req =3D {}; int rc, resp_len; - /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ - u8 buf[64 + 16]; =20 if (!arg->req_data || !arg->resp_data) return -EINVAL; @@ -132,8 +130,9 @@ static int get_derived_key(struct snp_guest_dev *snp_de= v, struct snp_guest_reque * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len =3D sizeof(derived_key_resp.data) + mdesc->ctx->authsize; - if (sizeof(buf) < resp_len) + resp_len =3D sizeof(derived_key_resp->data) + mdesc->ctx->authsize; + derived_key_resp =3D kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!derived_key_resp) return -ENOMEM; =20 derived_key_req =3D kzalloc(sizeof(*derived_key_req), GFP_KERNEL_ACCOUNT); @@ -149,23 +148,21 @@ static int get_derived_key(struct snp_guest_dev *snp_= dev, struct snp_guest_reque req.vmpck_id =3D mdesc->vmpck_id; req.req_buf =3D derived_key_req; req.req_sz =3D sizeof(*derived_key_req); - req.resp_buf =3D buf; + req.resp_buf =3D derived_key_resp; req.resp_sz =3D resp_len; req.exit_code =3D SVM_VMGEXIT_GUEST_REQUEST; =20 rc =3D snp_send_guest_request(mdesc, &req); arg->exitinfo2 =3D req.exitinfo2; - if (rc) - return rc; - - memcpy(derived_key_resp.data, buf, sizeof(derived_key_resp.data)); - if (copy_to_user((void __user *)arg->resp_data, &derived_key_resp, - sizeof(derived_key_resp))) - rc =3D -EFAULT; + if (!rc) { + if (copy_to_user((void __user *)arg->resp_data, derived_key_resp, + sizeof(derived_key_resp->data))) + rc =3D -EFAULT; + } =20 /* The response buffer contains the sensitive data, explicitly clear it. = */ - memzero_explicit(buf, sizeof(buf)); - memzero_explicit(&derived_key_resp, sizeof(derived_key_resp)); + memzero_explicit(derived_key_resp, sizeof(*derived_key_resp)); + return rc; } =20 base-commit: e180b3a224cb519388c2f61ca7bc1eaf94cec1fb --=20 2.46.2