From nobody Thu Sep 18 11:49:13 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 87B96C3A5A7 for ; Wed, 7 Dec 2022 01:02:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229843AbiLGBCt (ORCPT ); Tue, 6 Dec 2022 20:02:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229821AbiLGBCj (ORCPT ); Tue, 6 Dec 2022 20:02:39 -0500 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9BB7BC6 for ; Tue, 6 Dec 2022 17:02:34 -0800 (PST) Received: by mail-pj1-x104a.google.com with SMTP id o31-20020a17090a0a2200b00219a2904952so38173pjo.0 for ; Tue, 06 Dec 2022 17:02:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=LYb5Kkl7KCSyA25o8WI4Ic+8SfxAdiy9vbY0soW+D/8=; b=Pi2ZKrH8sVupiZlbc+zhoHxcKrCy9Td9o6yADcsSdTeQ0fbjZ+F/PZxeKNtHfFKZGY ya1GLHf7PmNpSghZ/GPX9Ckgrb7ovCtW8nKRE7sej87O/ZIC6c4GJWOQMqjTJNcm6gHi UdQy46PkhThDKH+wx7eWq0OeGcGL1LLc/h+wzh/QsRQ2X0RKtlho0JmQP+eZcxVeJM7h tbiHXnSgIFf89/MJk69ZIzWPhTSShdVexyk9q42ZCpqQC0vreRf5QBBGQyTpS8ZIzMcf HmlC/+ydM+hLQsGT+iSfJc6UU4p/H47/btHjSc7l9DjstB2Seb8YCA4MhPDyKuBsJ57c eyXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=LYb5Kkl7KCSyA25o8WI4Ic+8SfxAdiy9vbY0soW+D/8=; b=aVpudRnFh1/Uf05xGLXmZUrNcAcPDmq/N7CTG8uHLe0Ed1QhWm7VJQ4/hJp8b4W34Y DmROyYk2KHm2MFNIl9bpRL9iGpVbXZg8di+Y5DVQuqfAL9NN+uRmA6lfLdSocowMnf+Y ysF64HB0iEgMMFFSSuSFQiv60jMIwaPhyDD/dhA7ty91Ew5942tvAQ1YI9P1ZNmulmm1 a9PsYsm9dGYwCWDXZzbR3AUuWkYAIwqVGCt2S14HeticaiZ6oiKmPTicgf/FB0+D2VZo J8/dknYXDLhtdcjBiyV0+H7Tk0LQnt9It1G93NPYqRzXd0UgCQPrUroJvP3U41KIKmER YwPQ== X-Gm-Message-State: ANoB5pmpFsQebPL1tICr9ULq3mx0iZkGjra9G9Pec+T7LFn1blNNqINM T2A1eGK5Ho/BzyRPP1H7k2a+mD3LrJhMDEVYEpehpOIAUPA775rdOAtlIMLlp+M/d6vJzm/ikCt PLfW5Hf+4EtfiPdp2XJ3qO2Xj9PuAbn1OyQjXE7XXzpQlnec84y7zli7uS/EsGWzcD8PbteoYf1 mh2COWhxI= X-Google-Smtp-Source: AA0mqf79S2a8pHYPXB39OoGONxOXjRLJO03JVGSUEE07nKwCBsq1o57fflyv7qPwTVPzLRSSDqh70drKt+BYeGLeLg== X-Received: from dionnaglaze.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2ee6]) (user=dionnaglaze job=sendgmr) by 2002:a17:902:9004:b0:17c:9a37:72fb with SMTP id a4-20020a170902900400b0017c9a3772fbmr83968713plp.82.1670374953834; Tue, 06 Dec 2022 17:02:33 -0800 (PST) Date: Wed, 7 Dec 2022 01:02:09 +0000 In-Reply-To: <20221207010210.2563293-1-dionnaglaze@google.com> Mime-Version: 1.0 References: <20221207010210.2563293-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.39.0.rc0.267.gcb52ba06e7-goog Message-ID: <20221207010210.2563293-4-dionnaglaze@google.com> Subject: [PATCH v9 3/4] virt: sev-guest: Remove err in handle_guest_request From: Dionna Glaze To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Dionna Glaze , Tom Lendacky , Paolo Bonzini , Joerg Roedel , Peter Gonda , Thomas Gleixner , Dave Hansen , Borislav Petkov , Haowen Bai , Liam Merwick , Yang Yingliang Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The err variable may not be set in the call to snp_issue_guest_request, yet it is unconditionally written back to fw_err if fw_err is non-null. This is undefined behavior, and currently returns uninitialized kernel stack memory to user space. The fw_err argument is better to just pass through to snp_issue_guest_request, so that's done by passing along the ioctl argument. This removes the need for an argument to handle_guest_request. Cc: Tom Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Peter Gonda Cc: Thomas Gleixner Cc: Dave Hansen Cc: Borislav Petkov Cc: Haowen Bai Cc: Liam Merwick Cc: Yang Yingliang Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Reviewed-by: Tom Lendacky Signed-off-by: Dionna Glaze --- drivers/virt/coco/sev-guest/sev-guest.c | 35 ++++++++++++------------- 1 file changed, 17 insertions(+), 18 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index 1ea6d2e5b218..4a2a0a02985f 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -320,11 +320,11 @@ static int enc_payload(struct snp_guest_dev *snp_dev,= u64 seqno, int version, u8 return __enc_payload(snp_dev, req, payload, sz); } =20 -static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_co= de, int msg_ver, +static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_co= de, + struct snp_guest_request_ioctl *arg, u8 type, void *req_buf, size_t req_sz, void *resp_buf, - u32 resp_sz, __u64 *fw_err) + u32 resp_sz) { - unsigned long err; u64 seqno; int rc; =20 @@ -336,7 +336,8 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); =20 /* Encrypt the userspace provided payload */ - rc =3D enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz); + rc =3D enc_payload(snp_dev, seqno, arg->msg_version, type, req_buf, + req_sz); if (rc) return rc; =20 @@ -346,7 +347,8 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in * sequence number must be incremented or the VMPCK must be deleted to * prevent reuse of the IV. */ - rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); + rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, + &arg->fw_err); =20 /* * If the extended guest request fails due to having too small of a @@ -368,24 +370,22 @@ static int handle_guest_request(struct snp_guest_dev = *snp_dev, u64 exit_code, in * of the VMPCK and the error code being propagated back to the * user as an ioctl() return code. */ - rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, &err); + rc =3D snp_issue_guest_request(exit_code, &snp_dev->input, + &arg->fw_err); =20 /* * Override the error to inform callers the given extended * request buffer size was too small and give the caller the * required buffer size. */ - err =3D SNP_GUEST_REQ_INVALID_LEN; + arg->fw_err =3D SNP_GUEST_REQ_INVALID_LEN; snp_dev->input.data_npages =3D certs_npages; } =20 - if (fw_err) - *fw_err =3D err; - if (rc) { dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", - rc, *fw_err); + rc, arg->fw_err); goto disable_vmpck; } =20 @@ -432,9 +432,9 @@ static int get_report(struct snp_guest_dev *snp_dev, st= ruct snp_guest_request_io if (!resp) return -ENOMEM; =20 - rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_= version, + rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data, - resp_len, &arg->fw_err); + resp_len); if (rc) goto e_free; =20 @@ -472,9 +472,8 @@ static int get_derived_key(struct snp_guest_dev *snp_de= v, struct snp_guest_reque if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) return -EFAULT; =20 - rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_= version, - SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len, - &arg->fw_err); + rc =3D handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, + SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len); if (rc) return rc; =20 @@ -534,9 +533,9 @@ static int get_ext_report(struct snp_guest_dev *snp_dev= , struct snp_guest_reques return -ENOMEM; =20 snp_dev->input.data_npages =3D npages; - ret =3D handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg-= >msg_version, + ret =3D handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, &req.data, - sizeof(req.data), resp->data, resp_len, &arg->fw_err); + sizeof(req.data), resp->data, resp_len); =20 /* If certs length is invalid then copy the returned length */ if (arg->fw_err =3D=3D SNP_GUEST_REQ_INVALID_LEN) { --=20 2.39.0.rc0.267.gcb52ba06e7-goog