From nobody Wed Sep 10 21:51:20 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 A94EFC64EC7 for ; Wed, 1 Mar 2023 09:49:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229771AbjCAJtu (ORCPT ); Wed, 1 Mar 2023 04:49:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34754 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229602AbjCAJts (ORCPT ); Wed, 1 Mar 2023 04:49:48 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87128271B; Wed, 1 Mar 2023 01:49:46 -0800 (PST) Date: Wed, 01 Mar 2023 09:49:43 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1677664184; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AjBYcejPwwKYBVOYzMQ4TIcvZoumdc8c7sD67+6I5es=; b=HdmY4pdz68JHFhefmwNe20cjf3+25B0xeG5/Ca0Kq4QEeAeqdhZi4hXrzTGZ6kpbgDj0E6 X3aKQTG95SyOukBa50ucMVcA1TPuffRNN1nEQ+XnCuWTGz9lwC/+aPK8mtbYUILvdmjrox 5my3H1hL/XtvJCUv8p/RsNX0AuEGq15JYy+3t1xUpHGcDqGBJr8Z5V3GhLxIEo9pWDJt54 w/s3xv0EbEvHR/4x3xa3y/taMHRQX4rVQUd8HuMb++GYlXkzt8/hhVzdYxvTjq5YsXz4V7 7fEToIcGbw2fUXuwGeYPnxpGg87N5hxFBvgpN7TVd676yhOwwseuUDQeNJi4FQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1677664184; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AjBYcejPwwKYBVOYzMQ4TIcvZoumdc8c7sD67+6I5es=; b=K3w53KBk5fUtxxp4SG1yyrmNuQljW1V5ii6uBFPzpfsl5yv8aRLQkNBHO4BzkLeNPdDqRv EyeIe/RCIXNLD1Dg== From: "tip-bot2 for Tom Lendacky" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] virt/sev-guest: Return -EIO if certificate buffer is not large enough Cc: Larry Dewey , Tom Lendacky , "Borislav Petkov (AMD)" , , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: =?utf-8?q?=3C2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee=2E16770?= =?utf-8?q?83979=2Egit=2Ethomas=2Elendacky=40amd=2Ecom=3E?= References: =?utf-8?q?=3C2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee=2E167708?= =?utf-8?q?3979=2Egit=2Ethomas=2Elendacky=40amd=2Ecom=3E?= MIME-Version: 1.0 Message-ID: <167766418335.5837.8035431870442051850.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: dd093fb08e8f8a958fec4eef36f9f09eac047f60 Gitweb: https://git.kernel.org/tip/dd093fb08e8f8a958fec4eef36f9f09ea= c047f60 Author: Tom Lendacky AuthorDate: Wed, 22 Feb 2023 10:39:39 -06:00 Committer: Borislav Petkov (AMD) CommitterDate: Wed, 01 Mar 2023 10:17:46 +01:00 virt/sev-guest: Return -EIO if certificate buffer is not large enough Commit 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") changed the behavior associated with the return value when the caller does not supply a large enough certificate buffer. Prior to the commit a value of -EIO was returned. Now, 0 is returned. This breaks the established ABI with the user. Change the code to detect the buffer size error and return -EIO. Fixes: 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest dri= ver") Reported-by: Larry Dewey Signed-off-by: Tom Lendacky Signed-off-by: Borislav Petkov (AMD) Tested-by: Larry Dewey Cc: Link: https://lore.kernel.org/r/2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee.16= 77083979.git.thomas.lendacky@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/se= v-guest/sev-guest.c index 4ec4174..7b4e900 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -377,9 +377,26 @@ static int handle_guest_request(struct snp_guest_dev *= snp_dev, u64 exit_code, in snp_dev->input.data_npages =3D certs_npages; } =20 + /* + * Increment the message sequence number. There is no harm in doing + * this now because decryption uses the value stored in the response + * structure and any failure will wipe the VMPCK, preventing further + * use anyway. + */ + snp_inc_msg_seqno(snp_dev); + if (fw_err) *fw_err =3D err; =20 + /* + * If an extended guest request was issued and the supplied certificate + * buffer was not large enough, a standard guest request was issued to + * prevent IV reuse. If the standard request was successful, return -EIO + * back to the caller as would have originally been returned. + */ + if (!rc && err =3D=3D SNP_GUEST_REQ_INVALID_LEN) + return -EIO; + if (rc) { dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", @@ -395,9 +412,6 @@ static int handle_guest_request(struct snp_guest_dev *s= np_dev, u64 exit_code, in goto disable_vmpck; } =20 - /* Increment to new message sequence after payload decryption was success= ful. */ - snp_inc_msg_seqno(snp_dev); - return 0; =20 disable_vmpck: