From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 006133A8F4 for ; Wed, 15 Nov 2023 19:52:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="djoGbKFc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A651CC433C7; Wed, 15 Nov 2023 19:52:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700077945; bh=j0VGvbK+o+/o1RtSWGn3tYocUkhxf6Fn+lHIfwLEayg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=djoGbKFcv2tzsLY7B/BIFsbj4grD8lV/5ssGNtNdLP1eT6SJ9u9j2njJJ2fadps/o qIg0+ZCRvWtwm3EH8yQSeW+hc9Ww/jX4gx7+ljrOqx56PQs9Nv17Hb8+sKpq0jIroL HeKinMe1ADCbenO9AvTU3RIaMoZQ9tr2mW2cCGgY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dave Hansen , Adam Dunlap , Ingo Molnar , Jacob Xu , Sasha Levin Subject: [PATCH 6.1 014/379] x86/sev-es: Allow copy_from_kernel_nofault() in earlier boot Date: Wed, 15 Nov 2023 14:21:29 -0500 Message-ID: <20231115192646.004758661@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115192645.143643130@linuxfoundation.org> References: <20231115192645.143643130@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adam Dunlap [ Upstream commit f79936545fb122856bd78b189d3c7ee59928c751 ] Previously, if copy_from_kernel_nofault() was called before boot_cpu_data.x86_virt_bits was set up, then it would trigger undefined behavior due to a shift by 64. This ended up causing boot failures in the latest version of ubuntu2204 in the gcp project when using SEV-SNP. Specifically, this function is called during an early #VC handler which is triggered by a CPUID to check if NX is implemented. Fixes: 1aa9aa8ee517 ("x86/sev-es: Setup GHCB-based boot #VC handler") Suggested-by: Dave Hansen Signed-off-by: Adam Dunlap Signed-off-by: Ingo Molnar Tested-by: Jacob Xu Link: https://lore.kernel.org/r/20230912002703.3924521-2-acdunlap@google.com Signed-off-by: Sasha Levin --- arch/x86/mm/maccess.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index 5a53c2cc169cc..6993f026adec9 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -9,12 +9,21 @@ bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) unsigned long vaddr = (unsigned long)unsafe_src; /* - * Range covering the highest possible canonical userspace address - * as well as non-canonical address range. For the canonical range - * we also need to include the userspace guard page. + * Do not allow userspace addresses. This disallows + * normal userspace and the userspace guard page: */ - return vaddr >= TASK_SIZE_MAX + PAGE_SIZE && - __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); + if (vaddr < TASK_SIZE_MAX + PAGE_SIZE) + return false; + + /* + * Allow everything during early boot before 'x86_virt_bits' + * is initialized. Needed for instruction decoding in early + * exception handlers. + */ + if (!boot_cpu_data.x86_virt_bits) + return true; + + return __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); } #else bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) -- 2.42.0